The Reserve Bank says there is now $33.8 billion invested in KiwiSaver.
That compares to $21.4 billion two years ago.
The Reserve Bank says $18.7 billion is invested in New Zealand and $15.1 billion is invested offshore.
The investments are a mix of fixed income (cash and bonds), shares and commercial property.
The rapid rise in value is a combination of two factors: investment returns and additional contributions.
The bulk of the gains will have come from investment returns.
Morningstar's most recent survey showed that in the year to March 31 2016, the category returns were:
People who have invested from the start of KiwiSaver in the Growth or Aggressive funds will have larger balances (presuming they have made ongoing contributions) because they have a larger exposure to shares. The last few years have been good for world share markets.
Conservative funds have a majority of their investments in fixed income assets.
Those investments are expected to be less volatile and risky over the long term, but are also likely to deliver lower returns than shares (equities).