I just planted 35 seeds and got 25 females. Usually you get about 50/50 but there is something you can do to increase this ratio. I stumbled upon this by accident but I have heard from many a grower more experienced than I that this technique does increase the ratio of females.

Most people think that you have to keep the seedlings warm all the time but once they germinate I drop the temps to high 60s low 70s. I do this everytime with seeds. The last time I germinated 40 seeds and got 29 females. That's a pretty good ratio in my book. Try it, you won't be disappointed.