The Associated Press

WASHINGTON - Women's income is lower on average than that of men in part because they generally work less, leave the labor force for longer periods and tend to hold jobs that pay less, a congressional study found.

But even after adjustments for those factors, women still earned an average of 20.3 percent less than men in 2000, investigators said Thursday.

The General Accounting Office conducted the earnings study for Democratic Reps. Carolyn Maloney of New York and John Dingell of Michigan.

The 20 percent gap has been relatively unchanged in two decades. The difference was 19.6 percent in 1983.

The study could not explain reasons for the earnings difference.

Maloney and Dingell want to create a research center at a public university that would study potential solutions and publish information for employers and employees.

"After accounting for so many external factors, ... men get an inherent annual bonus just for being men," Maloney said.