In the end, vocations are still a miracle, as +ABL said decades ago.
...only the World is that much further downhill now. So if vocations were miraculous before, they're super-miraculous now.
I know a young man who was super interested in serving Mass. He was basically a Liturgy Nerd. He was not only a serious Catholic, but showed a lot of promise for having a vocation. As he approached 18, however, he was scandalized by the young lady(ies) at his chapel (I believe there was some romantic interest and/or courtship -- I don't know if it was mutual) and he eventually left to help the Indult with their liturgy, serving, and rubrics. Apparently he changed his mind at some point about trying out his vocation.
The thing is, I don't know what I would do if I were a young man today. The Resistance, for example, only has a seminary in Asia and France. Not exactly places I want to be. I specifically remember taking it as "God's will" that I not join the I.C.K.S.P. seminary, since they required first going over to Europe to learn French.
And I'll come right out and say it -- young men who are highly obedient to God/parents, attached to family, loving their mother (and parents, siblings) -- even going so far as "Momma's Boy" -- that's precisely the type of man likely to try out a vocation. Wouldn't you say? In the same way that a choleric person who thinks for himself, willing to argue, stand out, and speak up for himself is MORE LIKELY THAN MOST to become a Traditionalist. What Momma's Boy or good boy is going to want to go overseas and never see his family, when he grew up homeschooled and highly attached to his family?
Not saying the number is 0, but it's going to be a lot less than 100% of the original pool, if you know what I mean.