I think it depends on the growing conditions. Last year was my first year trying pumpkin. I had a horrible battle with powdery mildew and when that was nearly gone, the plants never made one female flower! I finally gave up and ripped them out...
This year I'm growing mystery squash that sprouted out of my compost pile. It could be one of a number of varieties as we went through every kind of squash trying to find our favorite (buttercup or turban, btw
). So anyway, these vines were transplanted and are quite healthy but only have male flowers so far.
I hope yours is doing as well. We can always try a little epsom salt in some water, it's supposed to encourage blossoms. Try 2 tbsp per gallon with a squirt of dish soap.