A quick search shows 381, counting short stories and young adult books. This doesn't count the roughly 80+ books that are or will be canon under Disney, currently out or at least announced.

I hand-counted on wikipedia back when Disney said that Expanded Universe wouldn't be canon so will trust your Google or other search. My count would not include anything Disney-related nor movie novelizations.

Point being, they're spending a lot of money and want to play it safe. You can do much more in a novel than a blockbuster movie. They do have decades of past original content to draw off of but there's most likely a larger general movie fanbase than those that did the deep dive into the books so might as well appeal to them.

"Similar but different".