Here and at just about every stop on her marketing blitz for Lean In: Women, Work and the Will to Lead, the ever-aspiring Facebook COO notes that women have constituted about 14% of top corporate jobs for the past decade.

This is true, according to Catalyst, the research firm that tracks women. But last evening, I had to speak up and remind Sandberg and her high-powered audience (including Gayle King, Lesley Stahl, A&E Network boss Abbe Raven, actress Katie Holmes and a few good men) that at the very top–the CEO level, that is–we have seen real movement.

In 1998, when Fortune started ranking Most Powerful Women, there was one woman solely in charge of a Fortune 500 company: Jill Barad, the CEO of Mattel . The Fortune 500 had one other woman chief executive back then, but she shared the top role with her husband: co-CEO Marion Sandler of Golden West Financial, which was later acquired by Bank of America .

Today, 21 Fortune 500 companies have women in charge. The list includes America’s two largest tech companies, IBM and Hewlett-Packard , and two of its biggest defense companies, Lockheed Martin and General Dynamics .

And this Catalyst chart shows the march of women into the CEO suite over the past decade: from 1.4% of Fortune 500 companies in 2003 to 4.2% today.

“Pathetic” is the word I used last evening to describe that 4.2%. But as I said to Sandberg, a decade ago we didn’t have role models for young women like Yahoo CEO Marissa Mayer and Sheryl herself–whom I wrote about on Postcards yesterday, comparing Silicon Valley’s two most powerful women and their distinctive paths to success.

Here’s a video clip of Sandberg last evening, in conversation with TIME Deputy Managing Editor Nancy Gibbs.

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