I can’t speak specifically to your question, but can report an anecdote, which will reveal my age.
In the 1950’s I did volunteer work at a children’s home run by what was then a small order of sisters, which has since merged with one of its parent or sister orders with the same name. They wore a full habit, somewhat simplified with less starch than the usual. One of the sisters said to me that they were very worried about the small entering postulants’ class of “only” nine postulants. I am quite sure that this was about 1956, certainly no later than 1960.
if there are fewer teaching sisters, which was what most sisters did then, there are going to be fewer sisters in the schools, and fewer sisters telling little boys that maybe they should think about becoming priests one day. The current NRVC-CARA study just published reinforces the impression that meeting religious and being encouraged by religious remains one of the driving forces for people to enter religious life.