I think the top two US cities when it comes to women cycling are Minneapolis and Portland and they are in the 40% range. So those of you who are claiming near parity are almost certainly mistaken.
Nationally, cycling by women and children appears to have been decreasing for some time:
http://www.gluskintownleygroup.com/d...w%20Report.pdf
I would love to see this trend reverse but I think the media and advocacy drumbeat that exaggerates the dangers of cycling has had a very negative impact on more cautious riders.