They say that in traditional Ball Golf, women make up about 20% of playing population (statistic from hearsay, admittedly)
I've heard that disc golf is at a much lower rate than that at 7-10% (or lower) estimated.
However, like you, we often notice more females "around" the course which makes us think there is a larger representation than first imagined.
To add - the Showdown likely had a higher than average female participant pool. A lot of female to female promoting took place to get the attendance that was seen. (most of that happening here on this forum) And even then, look at the PDGA registrant page for the event and see if they didn't come in a little over the 10% mark.
I know up here in West Sound, we're actively looking to craft many of our events to broaden our disc golfing demographic beyond "the usuals". Time will tell if we start being successful at it, as I imagine attracting wider demographics to the the sport is a slow and steady process over time, rather than expecting an explosion.