It seems women my age forgot to make babies:
More Women Than Ever Are Childless, Census Finds
I like the explanation: "Clearly women have competing alternatives for the use of their time..." Like we choose between motherhood and taking Pilates.
When I first read this I thought, "Twenty percent, no way! Everyone I know has kids." But then, the more I thought about it, the more women I remembered who do not, or did not give birth (adopted kids). 20% has started to seem plausible.
Another benefit of a feminized society?