For reference, here's a chart I made a few months ago of female and male YC founders accepted into Y Combinator by year: http://i.imgur.com/MCLqUm3.jpg (from https://medium.com/p/2613f58e5082 )

EDIT: The percentages in chart are # female founders accepted into YC / # founders accepted into YC. The 24% statistic in the article is number of startups with at least 1 female founder, so the chart may be biased lower than that statistic.