Birth control was available to the Baby Boomers's parents, and the result was... a baby boom. My two grandmothers had 7 and 5 children respectively in spite of the availability of birth control.
Griswold was in 1965. We had laws banning birth control.
The Pill was first used in 1960.
Yes, condoms existed. But they were stigmatized, sometimes criminalized, and substantially less effective than hormonal birth control methods developed and popularized during the 60s and 70s.
You've just moved the problem to explaining why "the percentage of the population taking birth control has increased significantly since that time".
Your initial claim was that it was the availability of birth control. That is, that birth control was the cause. But this new claim is that it is the choice to use birth control. That is, choosing to use birth control is now an effect, which must have some other cause.
The Pill was first used in 1960.
Yes, condoms existed. But they were stigmatized, sometimes criminalized, and substantially less effective than hormonal birth control methods developed and popularized during the 60s and 70s.