Lets take the US as an example;
There were around 37m females in the US between 15-34 in 2004. Lets cut out 7m for those aged 15-17.
Now think how many naked chicks you've seen online.
How many of those 30 million have taken their clothes off for the camera?
Lets say you've been looking at porn online since 1996. Lets say on average you've seen 50 new naked girls online every day. Realistically it's probably higher than this (look in your history folder over the past 3 days), but lets count for days you didn't fap etc.
(50 * 365) * 15 = 273,750
Lets say 3/4 of them were from the US. That's not a bad estimate since by far the majority of porn comes from the states. It leaves 205,312.
Mind = not very blown.
Thread: How many girls have done porn?