Although women make up nearly half of the U.S. workforce, only 16.6 percent have seats on the boards of Fortune 500 companies and the number has barely budged since 2005, according to a newly released study, Reuters reported. The Catalyst 2012 F500 Census, which annually tracks women in top positions in companies, showed progress is painfully slow for women seeking the top spots in corporate America, with only a 0.5 percent rise from the previous year.

"What we found is that the needle barely budged for women aspiring into corporate board service or into top-level leadership at these very prominent American companies," said Rachel Soares, a senior research associate at Catalyst, a non-profit group. "In 2012 women held only 16.6 percent of board seats and only 14.3 percent of executive officer positions."

The number of women executives last year was slightly lower than in 2010 and only marginally better than in 2011. During the past two years more than a quarter of U.S. companies had no women executive officers, according to the research, and just one-fifth had 25 percent or more.