Try the Official Catholic Directory published by PJ Kennedy. Each year the book contains all kinds of statistical information, including just what you’re looking for.
They don’t make that information available online (after all, they are a business, and they make their money by selling the books), but almost every Catholic parish in the country will have one of these in the parish office (at least every parish with enough resources to buy a new one every year!).
Just go to the nearest (big) parish, or try a library (many bigger public libraries and most Catholic college libraries have these).
PS If I could, I would simply give you the statistic you’re asking about, but my parish isn’t one of those with enough resources to buy an updated copy every year.