The year that the rich started getting a lot richer

Think 1982, according to a paper by two Northwestern University economists. That was the year the top 1 percent began seeing their share of the nation's income take off after decades of relative stability. In 1980, their share of income was 8 percent; by 2008, it was 17 percent. From the paper:

Prior to the early 1980s, the incomes of high-income households were more often than not less cyclical than the incomes of average households. But since around 1982, the incomes of high-income households-- the top 1% of the income distribution and higher - have become highly exposed to the fluctuations in aggregate income, with the incomes of the top 1% being more than twice as sensitive to aggregate income fluctuations as the income of the average household.

So why the fluctuation? Perhaps technology played a role.

The rise of information and communication technologies (ICT) has allowed the most skilled in any given area to apply their talents to more -- to manage more workers and capital, entertain more people, and write more papers....This change has raised the size and profits of the best. We argue that the highest earners have larger fluctuations in their earnings than the rest of the population, because individuals who operate at a large scale naturally will have very cyclical earnings."

The Wealth Report's Robert Frank offers two other possibilities: A drop in the marginal tax rate and deregulation of the financial industry.