Yeah, I was surprised by that survey. In fact, I just plain don't believe it. For one thing, my generation (adolescents in the late sixties/randy youth in the seventies) definitely did more than its share. Most women I know from that time number lovers from the tens to the hundreds. So, you know. There would have to be lots of enuchs in the generations following to average out to "two."
Even for the post-AIDS generation numbers weren't all that low. When I taught at SUNY Plattsburgh, students were forever coming in Mondays all woozy, and saying things like "God, I got so drunk last night, I have no idea what I did!" Other students would fill in the details about their amnesiac peers: mostly, they fucked. My son also tells me that a fair number of girls act one way sober and another way drunk. So, maybe, one reason the numbers are low is that people don't count what they do when they're drunk...cause they "don't remember."
Also, I don't think not having enough "time" matters for sex. I mean teens, people in their twenties, and people without kids can always find the time.
Joanna