CREATE TABLE table_203_610 (id DECIMAL, "institution" TEXT, "location" TEXT, "nickname" TEXT, "founded" DECIMAL, "historical affiliation" TEXT, "enrollment" DECIMAL, "primary conference" TEXT)

how many institutions have a private historical affiliation ?
SELECT COUNT("institution") FROM table_203_610 WHERE "historical affiliation" = 'private'
SELECT COUNT("institution") FROM "table_203_610" WHERE "historical affiliation" = 'private'