Does your 4% only count those who abstain?
I can assure you, I was not one of those. Never have been. Yet staring 40 in the face, I have somehow managed never to get knocked up.
Do you really think that I, who got out of high school in 1986, was better informed about the way the body works than a teenager whose sex ed is far more recent?
You're assuming Bristol had some kind of sex ed. Palin preaches abstinence only. That's probably as far as it went with Bristol.