In my fairly long experience of training, the number of professional women pilots is roughly proportional to the number who really want to do it.
Women don't seem to be encouraged towards aviation as a career by educational organisations (in spite of the efforts of the British Women Pilots Association). They don't habitually read aviation magazines when they are young or generally turn up at hangars and pump fuel/clean aircraft etc. It quite often seemed to be the case that their interest in becoming pilots was rather a late thing after considering other careers, hence they didn't show up well during selection, unless they had family connections in aviation.
However, those who really wanted to do it and put in the effort often came out better than their male counterparts.