I'm not sure if those numbers are publicly available.
If I was to take a wild guess... I would say that it's usually around a few dozen.
If you are concerned about making the connection... don't be. There's two hours between the trains, but #3 has very good on time performance and frequently arrives early into Los Angeles. If for some strange reason #3 is running really late, Amtrak can always hold #14 or put passengers on a bus, van or taxi to catch up.