The wealth of the richest group in the United States has rapidly expanded in recent year, widening the earning gap between the rich and the poor. The earnings of the highest one percent of the population accounted for 21.2 percent of American total national income in 2005, compared with 19 percent in 2004. The earnings of the lowest 50 percent of the population accounted for 12.8 percent of the total national income in 2005, down from 13.4 percent in 2004 (Reuters, October 12, 2007). The number of "ultra-high-net worth" US households, that is, those with a net worth of 5 million US Dollars or more, excluding the value of their primary homes, reached 1.14 million in 2006, a 23 percent rise from 930,000 in 2005 (Richest Households Pass 1 Million Mark, CNNmoney.com, April 17, 2007). The number of billionaires increased from 13 in 1985 to more than 1,000 in 2006 (The Observer, July 24, 2007). Top executives of major US businesses made an average of more than 10 million US Dollars in 2006, 364 times over that of ordinary workers. They earn as much money in one day of work as ordinary workers make over the entire year (AFP, January 4, 2008).

The past five years have witnessed relatively strong growth in the US economy, but the fortunes of millions of Americans just get worse. The ratio of American wage expenditure to gross domestic product (GDP) has dropped to the lowest since records began in 1947. The average income of households consisted of members at working age has seen a continuous decline in the past five years, and is 17 percent less than five years ago (US News & World Report, January 1, 2007). According to a national survey on the state of stress in America conducted in September 2007, money and work were the biggest stressors for almost three-quarters of Americans. Of the 1,848 adults polled, 51 percent worried about housing costs. Housing was a "very significant or somewhat significant" source of pressure for 61 percent of the residents in the West and 55 percent those in the East (USA Today, October 24, 2007). According to a latest report by the US government, suicide rate among Americans aged 45-54 rose by about 20 percent from 1999 to 2004, the highest since records began 25 years ago (The Associated Press, December 14, 2007).