Fortune’s Power Women: five facts, and why Oprah didn’t make it by Patricia Sellers @FortuneMagazine October 10, 2013, 8:45 PM EST E-mail Tweet Facebook Google Plus Linkedin Share icons When Fortune published its first Most Powerful Women in Business list in 1998, there was Carly Fiorina at the top and not a huge amount of power underneath. Relatively speaking, that is. That 1998 Fortune MPW list included just two Fortune 500 CEOs: Jill Barad of Mattel and Marion Sandler, who was co-chief of Golden West Financial with her husband, Herb. The 2013 Fortune MPW list, released this morning, includes 20 Fortune 500 CEOs. At the top: Ginni Rometty of IBM . Fifteen years ago, most of the Fortune MPW were in the consumer packaged goods and media industries. The 2013 list features consumer-products stars–PepsiCo chief Indra Nooyi, Mondelez CEO Irene Rosenfeld and Procter & Gamble’s Mel Healey and Deb Henretta. But women in tech dominate the new rankings. The 2013 top 10 includes five tech execs: Rometty, Facebook’s Sheryl Sandberg (No. 5), Yahoo chief Marissa Mayer (No. 8) and Hewlett-Packard boss Meg Whitman (No. 9). If you doubt that women overall are gaining power in corporate America, consider: Women run the two largest tech companies in the U.S.: IBM and Hewlett-Packard. Lynn Good, a newcomer to the list, heads Duke Energy , the biggest U.S. electric utility. And Marillyn Hewson (No. 4) is CEO of the world’s largest defense contractor, Lockheed Martin . The 2013 MPW list includes four women in defense, vs. no defense-industry executives in 1998. There are lots of moms on the 2013 MPW list (all of the top 10 except Rometty). And in general, Fortune’s MPW are getting older. Average age: 53, vs. 48 in 1998. And why are the MPW aging? In part because their businesses are getting bigger: Today’s Fortune MPW typically oversee at least $6 billion in sales, vs. $1 billion or so 15 years ago. Experience, as well as size, matters. And for the first time ever, one woman who has always made Fortune‘s MPW list dropped off: Oprah Winfrey. Her cable network, OWN, seems to have overcome its startup struggles and is drawing bigger audiences, but the business isn’t big enough to put Oprah, No. 50 last year, on the 2013 list. To learn more about the 2013 MPW list and the star leaders on it, watch today’s CBS This Morning segment, where I revealed the rankings with Gayle King, Norah O’Donnell and Charlie Rose.