This has seemed prudent to thousands of New Zealanders, partly because house prices have increased strongly in recent years.
And while to some extent it does make sense to anticipate future income growth, the ratio of house prices to incomes is currently at historically high levels - the sort of levels reached in the mid-1970s, just before the very sharp fall in real house prices in the second half of that decade, or in the United Kingdom before the savage correction in the late 1980s and early 1990s.