During my 9 years career in the IT I have encountered few girls in the IT industry even fewer in the dev domain.
Besides those who are, are not really passionate with what they are doing and consider changing career whenever the opportunity arises.

For example, I donno the number of girls in in this forum but I can expect that it is much lower than the number of guys.
It is strange to notice this fact:s and still helpless cncerning it interpretation and the reason behind.