WATCH: Everything you need to know about KiwiSaver in 60 seconds

KiwiSaver celebrates its 9th birthday today. Photo/Getty Images.

When former finance minister Michael Cullen first talked about KiwiSaver in 2005 official expectations were that around 5 to 10 per cent of the population would sign up to the voluntary savings scheme.

Nine years on from its launch on July 1, 2007 more than 2.6 million people - well over 50 per cent of the population - are in the scheme and more than $33 billion is invested.

When KiwiSaver launched - ahead of the global financial crisis - balances were low when crisis hit meaning little damage was done to people's savings and the reputation of the scheme.

Since the crisis markets have rebounded strongly, giving savers access to one of the longest bull runs in share market history.

In the last three years alone the amount of money in KiwiSaver has more than doubled from $16.5 billion in March 2013 to $33.9 billion in March of this year.

But KiwiSaver has not been without its teething issues.

While the number of people in KiwiSaver is high the percentage who are actually saving is far lower.

A million members were classified as "non-contributors" in last year's annual KiwiSaver report because they did not put any money into KiwiSaver in the two months prior.

Around 350,000 members are under 18 years of age and may not be putting any money in.

Sign-ups of children have also slumped since the 2015 Budget when the $1000 kick-start was cut immediately. This was the only incentive available to children.

The National-led government has continually watered down incentives for KiwiSaver since it came into power.

It halved the annual member tax credit from $1042 to $521 and now taxes the employer contribution, effectively hitting how much savers are getting into their accounts.

National has also talked up plans for auto-enrolment of all workers over 18 but has delayed its introduction because of the added cost.

As well as a retirement savings scheme KiwiSaver is now widely used by Kiwis to buy their first home.

People are able to take all of their savings out of KiwiSaver apart from $1000 to buy or build a house after being in the scheme for more than three years.

More than 47,000 people have used money from KiwiSaver to buy a home and that figure is growing daily.

At the same time a growing pool of retirees is gaining access to their money at 65.

In the year to March 2015 retirees withdrew $422 million although many are also choosing to leave their savings in KiwiSaver because of the low interest rates available at the bank.