Millionaire ranks grow

The U.S. and Canada saw a 15 percent increase last year in the number of seven-figure households, according to a study by Boston Consulting Group, largely the result of the stock market climb. The 4.7 millionaire households in the U.S. account for a smaller percentage of the population than in 2007, but they control a greater percentage of the wealth (55.2 percentgae in 2009 versus 55.1 percent in 2007).