But the dramatic slump, which is also affects Brent crude that New Zealand imports, ought to more than offset the 4 per cent decline the kiwi dollar has seen in the same period.
Commodity analysts fear the sell-off may have some way to go after Saudi Arabia revealed it raised output back above 10 million barrels a day in February, reversing about a third of the cuts it made the previous month.
There are big economic implications, too.
The historic slump in fuel prices began in 2014 and exacerbated deflationary conditions around the world, prolonging a period of historically low interest rates.
Oil prices bottomed out in late 2015 and have been in recovery mode since.
A lot now depends on whether these oil price falls are sustained but the new trend has some economists worried.
Late last year the OPEC group of oil-producing nations agreed to production cuts which accelerated the recovery.
In tandem with a US economic recovery that had fuelled hopes that more normal inflation levels were returning to the world economy.
A lot now depends on whether these oil price falls are sustained but the new trend has some economists worried.
It is unlikely to affect the thinking of the US Federal Reserve which is expected to raise interest rates later this week.
But it will have serious implications for the rate outlook if the trend continues.
A Bloomberg report quotes Goldman Sachs research saying the rally in US credit has left little "buffer for shocks."
Meanwhile, keep an eye on your local petrol pump. Prices shouldn't be rising any time soon.
Minister Collins has said she expects her report back by the end of June.
