The number of U.S. millionaires grew for the fourth straight year in 2012, but still has not reached its pre-recession peak of 2007, according to Spectrem Group.

The number of households with $1 million, not including primary residence, grew by 400,000, to 8.99 million in 2012, after hitting a low of 6.7 million in 2008, according to Spectrem. The number peaked at 9.2 million in 2007.

Most other wealth categories are also growing and remain short of their 2007 numbers, according to Spectrem. The only group that now exceeds its 2007 total are those with more than $100,000 in liquid assets.

The ultra-high-net-worth, with $25 million or more in net worth, grew by 10,000 last year, to 117,000 from a low of 84,000 in 2008.

Those with $5 million or more grew by 62,000 for the year, to 1.14 million, after hitting a low of 840,000 in 2008. Those with $500,000 or more rose to 14.3 million from 13.8 million the year before and from 11.3 million in 2008.

Those with $100,000 or more climbed to 37.4 million, from 36.7 million in 2011 and a low of 31.2 million in 2008.

“While the ranks of investors with at least $100,000 in net worth have finally surpassed the previous 2007 high, the numbers of households at the higher wealth levels are still below their 2007 highs,” says Spectrem. “In general, though, those with more wealth have been better able to weather the downturn because of the diversity of their investments and willingness to stick, in part, with stocks.”