This is actually a shocking state of affairs, given that in 1985 this number was 37%. That blatantly suggests (to me at least) that there's no gender-related skill differential in this field, and instead women are being discouraged for other reasons.
I would expect to see around 20% of girls.
http://blogs.computerworld.com/sites/computerworld.com/files...
Which makes me question the quality of the list.
At my university in engineering and applied sciences ( weird but that's the official translation in English ), one of our teacher was the first woman to graduate. She was very good, she had to be better than the average to prove that the school did not make a mistake in letting her in.
Given the low overall enrollment, it wouldn't surprise me if the ones who "bother" to join the CS program are more driven and intrinsically motivated than the average. Given that drive and intrinsic motivation are likely highly correlated with excellence within their peer group, it seems well within reason that a minority group overall would be over-represented in the elite set.
But that's true about the guys too. People who don't like programming get weeded out pretty quickly from CS.