I bet you are thinking of births out-of-wedlock, which is 73% among blacks. And single parent families among blacks is 67%.
Back in 1960, before the “war on poverty” the out-of-wedlock rate was something like 20-25% for blacks. Still much higher than the national average back then (about 7%).
Yes I think your right..sorry for the mistake..the 70 percent stuck in my head I knew I had heard it from somewhere..thank you for the correction