
Source: http://www.brillig.com/debt_clock/
Economics, as a branch of the more general theory of human action, deals with all human action, i.e., with mans purposive aiming at the attainment of ends chosen, whatever these ends may be.--Ludwig von Mises

Taxing capital gains at a lower rate than ordinary income is a long-established policy to encourage risk taking and investment. Since we already tax corporate earnings at 35% through the corporate income tax, taxing those profits again when the stock is sold imposes a double tax on risk capital. That's why 12 industrialized nations, including Hong Kong and Korea, impose a zero capital gains rate.
The income groups refer to percentiles of tax filers ranked from those with the highest AGI to those with the lowest AGI. The figure shows the highest-income groups on the left and the lowest-income groups on the right.
1990 was before the Clinton tax increases of 1993. 2000 was after the modest tax cuts of 1997, but before the Bush tax cuts of 2001. 2005 was with the Bush tax cuts in place.