The amount of productive New Zealand land in foreign hands is probably around 10 per cent - and growing.
It is undoubtedly higher than the 2 per cent of rural land figure Prime Minister John Key drew on when attempting last week to defuse the row over the Chinese bid for Lochinver Station near Taupo.
It's certainly less than the "500 rugby fields a day" Labour's David Parker this week claimed has gone to foreign buyers in six years under the National-led Government.
Somewhere in between lies the truth.
An accurate picture of how much land is overseas-owned would seem essential to any debate on the pros and cons of foreign control over "our" land. But attempting to measure foreign ownership is a mathematical puzzle complicated by joint ventures, leasehold deals and limited historical data. It doesn't help that until 1998 Government agencies thought it unnecessary to record the countless land purchases made by overseas investors.
In the vacuum, prejudice and politicking can flourish.
But drawing on just a few pieces - the long-established overseas dominance of our forestry and wine industries and the spate of recent approvals in agriculture - it's soon clear that investors from America, Australia, Europe and China are beating a steady path to our door, and have done for more than 20 years.
Close to 1 million ha in plantation forests alone is in foreign hands (either full ownership or management). In 2010, the Forest Owners Association reported that 317,000 ha were overseas owned, with forestry investment and management firms controlling a further 654,000 ha in leases.
In the wine industry, it is estimated that between 40 per cent of wine produced is ultimately owned by foreign companies.
Back in 2003, the Overseas Investment Office (OIO) was comfortable with an estimate that 1 million ha of rural land was owned by foreigners. The ballpark figure came from the Campaign Against Foreign Control of Aotearoa, which monitors overseas investment decisions.
OIO records show that from 2001 to 2013, a total 1.6 million hectares of freehold land changed hands in transactions requiring overseas investment approval. That's more than 10 per cent of the country's estimated 14.5 million ha of productive rural land.
But here's where things get complicated. Many sales are joint ventures or otherwise involve multiple parties, including New Zealanders. Though the overseas investor may have a controlling hand, the OIO calculates a "net" land area which is deemed foreign-owned - reflecting the percentage of the foreign stake in the purchasing company. According to the OIO, the "foreign" component of those 1.6m ha in freehold sales comes down to 562,000 ha.
Another difficulty is that many sales involve land already in overseas hands.
Then there are leasehold arrangements, where foreign companies may control and profit from long-term land use without full freehold rights. Some 358 leasehold deals covering 707,500 ha were approved from 2001-13, with the overseas component a net 279,000 ha.
The OIO also cautions that not all sales proceed and that some overseas buyers become NZ citizens or permanent residents.
"Tracking sales and establishing whether the purchaser is a New Zealander or not ... potentially requires an infinite and complex monitoring regime," chief executive Annelies McClure said in a statement.
Council of Trade Unions economist Bill Rosenberg is a stalwart of the Campaign Against Foreign Control Aotearoa (Cafca). In 2012 - after Key had claimed fewer than 1 per cent of farmland was overseas-owned - Rosenberg produced a "conservative" estimate that 3.2 per cent of farmland was in foreign hands. Adding forests, his estimate was an again conservative 8.7 per cent.
Rosenberg analysed six years of approvals after the 2005 Overseas Investment Act was passed and used older statistics going back to 1991. He found a trend of high sales in the 1990s, a slowdown in the 2000s and a recent acceleration in interest in farmland. In 2011 alone, 173,600ha of freehold and leasehold interests in forests and farmland went to overseas buyers.
If leasehold interests were included, it was possible that 10 per cent of farms alone were under foreign control, he concluded. Since then foreigners have been handed the keys to another 130,000 ha of freehold land and 90,000ha in leases.
Rosenberg supplied the Weekend Herald with updated figures, using year-on-year OIO reports since 2001. He found that 2.3 million ha - 16 per cent of productive rural land - changed hands in freehold and leasehold purchases from 2001-2013. The "net" foreign component was 841,000 ha.
In downplaying the foreign footprint, John Key has said the Government would act to slow down any "serious run" on New Zealand land. But what constitutes a run?
The OIO approved just over 2000 applications (mostly freehold) in the 12 years to 2013, an average of 156 a year. Numbers spiked in the early-2000s and have since been steady. But in 2011 and again last year, there were spikes in the amount of agricultural land (particularly with dairying potential) involved.
This hasn't stopped Key playing politics: he claimed last week that the area sold under National was around half that which occurred under Labour. He was being selective with his stats - seizing on Labour's final term which included the huge Carter Holt Harvey forests sell-off in the central North Island, to US timber investor Hancock. Parker (a former Land Information Minister) was equally selective with his rugby fields line. Rosenberg's figures show annual freehold sales under both regimes, on average, running neck and neck at 43,000 ha.
How much is too much? Proponents cite benefits including job creation, increased development, innovation and added-value from funding which New Zealanders are unable to provide.
Opponents argue about profits disappearing overseas, "business culture" differences, loss of control over land, and, ultimately, loss of sovereignty.
The OIO's task is to satisfy itself that the benefits to New Zealand will be "substantial and identifiable". Applicants may promise a range of positives including jobs, export receipts, new technology, consumer benefits, additional development and environmental protection or enhancement.
The drawn-out sale of the 16 Crafar farms in the central North Island alerted New Zealanders to the overseas interest in dairying, the engine room of our economy. That the bidding for the run-down, polluting farms was led by Chinese investors troubled those who fear a loss of control, associated in part with China's unquenchable thirst for quality milk products.
The OIO is monitoring progress with the joint venture between Shanghai Pengxin and state-owned Landcorp and, last November, released the company's first annual report. Despite last year's drought, the report highlights gains including improved animal welfare, infrastructure improvements and environmental enhancements -- though many would argue progress was a no-brainer given the state of the farms.
Pengxin has this year taken a controlling stake in Synlait Farms Ltd, owner of 13 dairy farms covering 4500 ha in mid-Canterbury.
Pengxin is also the applicant to buy the 13,800 ha Lochinver Station near Taupo, for $70 million.
Should we be worried about growing Chinese interest in New Zealand dairy farms when German and American investors have been snapping up paddocks throughout Canterbury, Otago and Southland?
Financial commentator Bernard Hickey noted in his Herald on Sunday column last week that the recent Chinese presence may be just the tip of the iceberg - a "wall of cash" is about due to flow from China into investments in foreign land, mines and properties.
Federated Farmers - usually supportive of rural investment - is officially uneasy, with many farmers concerned that the "corporatisation" of farming could end the family farming tradition. It's worried that Pengxin's strategy may be to "vertically integrate" - controlling everything from the production of milk to the supermarket and arguably competing with our own corporate giant, Fonterra.
Its president William Rolleston told Fairfax: "Given the location of these farms to Shanghai Pengxin's [Crafar] landholdings, it will increase speculation that vertical integration by way of processing could be on the cards.
The proposed sale "again highlights the need for research into what the extent of overseas investment in our farmland is," he said.
Federated Farmers last year wrote to ministers requesting such research. "We understand ministers were concerned at the potential cost, but the economic price of getting foreign investment rules wrong outweighs this."