The original is here at Cardinal Newman Society, scroll about halfway down
I think it's relevant to this thread because it shows a precipitous losing streak for Catholics in the U.S., starting way before the USCCB's present reincarnation as the Democratic Party at Prayer.
Couldn't be clearer that the precipitating catastrophe was Vatican II. The rest of the indicators go straight down the slope from 1965, which was the closing year of the Second Vatican Council.
Thank-you for posting the graph and I agree with your comment about the Second Vatican Council and it effects.