For YLS during the 2019–2020 school year, it was Yale (90), Harvard (54), Columbia (34), Princeton (31), Stanford (22), Dartmouth (21), Cornell (19), Chicago (18), Brown (17), Pennsylvania (16), Georgetown (13), Berkeley (13), Duke (10), and all other institutions were represented in the single digits. The eight ivy league schools alone comprises 41% of all students enrolled.
They stopped doing a headcount after 2021 but I’d assume it’s the usual suspects: Ivy League and Ivy + institutions (with the exception of MIT)