How often do you flop 2 to a flush of the suit you hold?

[Rayek]

I was looking in my pokertracker database of 11k played hands, and was losing slightly on AKs and AJs. I was curious why, and was looking through the hands. Turns out, in being dealt AKs 40 times, I have not hit the flush once. In 41 hands of AJs, I have made my flush once. Now Im sure that there are other combinations of suited hands where I have made the flush more than my fair share of the time, but I was just curious when you have 2 of a suit, what the probability is that you will make a flush by the river? I have read that when you flop the 2 to a flush, you are 35% likely to complete it by the time the river comes, but what about before the flop? Thanks in advance.