The number of millionaires in the US jumped by 16 per cent last year after slumping by 27 per cent in 2008, a report showed.

Last year, some 7.8 million US households had a million dollars or more in investable assets - not counting capital invested in their primary residence, the report by the Spectrem Group shows.

That was up by 1.1 million from the year before, when the number of US millionaires fell to its lowest point since 2003, hitting 6.7 million as the US economy stumbled.

“While still well short of its all-time high of 9.2 million in 2007, this year’s growth in the millionaire population is nevertheless welcome news for an economy still working to recover,” said George Walper, president of Spectrem Group.

The number of quintuple-millionaire households - with assets worth more that five million dollars - was also up last year, climbing by 17 per cent to 980,000 from 840,000 in 2008.

And what the report calls “the broader aff-luent population”, made up of households with a net worth of half a million dollars or more, grew by 12 per cent last year to 12.7 million.

US millionaires were 62 years old on average while the average age of the ultra-millionaires - people with assets in excess of five million dollars - was 67.

The majority of the “mass afflu-ent” fell between the ages of 51 and 64, with an average age of 58.

Senior corporate executive was the most common occupation listed by the ultra-rich, with a quarter of the five-million-dollar households saying they worked as high-ranking executives in corporations.

The most-listed occupation among the mass affluent and simple millionaires was that of manager.