In the Book Market Guide from ICL, I see stats the publisher provides. Ex:
Chronicle Books pubs 170 titles annually. Receives 20 queries, 1000 unsol mss monthly.
Clarioin Books pubs 35 titles annually; 8% developed from unsol. subs, 70% by agented authors, 30% by authors who are new to this house, 8% by previously unpubbed writers. Receives 40 queries, 300 unsol. mss monthly.
Candlewick pubs 200 titles annually, almost all by agented authors, 1-10% by authors who are new to the house, 1-10% by previously unpubbed writers. Receives about 500 queries monthly.
You probably want to research this house by house.
Vijaya