@le_inferno Actually, because most of the studies are actually done by the birth control companies, they write off cases of incorrect use. Those statistics only include correct use of birth control and condoms—the statistics including incorrect use are much closer to 70% or 80%, I believe. I’ll see if I can find those specific numbers.
Update: Okay, here we go. The numbers are higher than I thought, but still useful to know.
Condoms, ideally (that is, used properly), are 97% effective. Typically they are 84% effective.
Oral birth control, ideally, is 99–99.9%. Typically it is 92–95% effective. (The range is for different kinds of pills).
These numbers are all pretty high, but repetitive use drives the likelihood of a mishap up exponentially, which is why it’s so important to use them properly so you can safely have lots of sex!