I've found about 5 villages that seem to spawn the "Clerics" and "Librarians" more often than any other villager type, with the farmer spawning the fewest of all. This has been checked on both Superflat and Regular world types, the game seems to prefer the Cleric and Librarian more so than the farmer or butchers.

I found a village with only 1 library, but it spawns half of the villagers population as a librarian out of 20. I also found the same villages didn't have a church and it still there were about 6 Clerics/Priests out of the 20 villagers. I checked more villages and found that the Librarian and Priest spawned more often than others. I looked if a blacksmith building was there and there wasn't, but still blacksmiths were still in the village.

I don't think this was intended, it wasn't like this on 1.8.