It happens the average is really hard to predict I can tell
My first season working with CG I produced no female out of 50 CG offsprings, meanwhile a good friend of mine produced 1 female in every clutch that season.
Since I have produced 2 females I have probably produced around 200 CG combos now, my friend still produce females at a higher rate than I do.
Some people will say it's about 2 to 3 percent I am below that.