(Blooomberg) — Women and minorities remain underrepresented in U.S. corporate boardrooms, crimping companies’ potential to lead in the global economy, a report by the Alliance for Board Diversity showed. White men held 73 percent of board seats at Fortune 100 companies last year, up from 71 percent in 2004, according to the alliance, which advocates the inclusion of women and minorities on corporate boards. White women accounted for 15 percent in 2010, compared with 14 percent in 2004, while minorities made up 13 percent, down from 15 percent. Citigroup Inc. (C), International Business Machines Corp. (IBM) and Procter & Gamble Co. (PG) were among just 15 companies in the Fortune 500 whose boards last year had representation from each of the U.S. Census Bureau’s major groups: men, women, Whites, African Americans, Asian Pacific Islanders and Hispanics, the alliance said. Companies won’t reach their potential without leaders from different backgrounds, ethnicities and genders, it said.