On the municipal end there are quite a few female muni traders. I don't know the percentages but the company I worked for it was close to 50/50. However, in the bigger company I worked for it was more of 85/15.
I did do business with quite few buy-side women on the fixed income side. For the most part, they were really cool, I got along well with them. There was nothing in their DNA which made them any less capable at their jobs.