CREATE TABLE table_28404 ("Institution" TEXT, "Location" TEXT, "Nickname" TEXT, "Founded" FLOAT, "Type" TEXT, "Enrollment" FLOAT, "Joined" TEXT)

How many different items appear in the enrollment column that joined in 1931, 1949 1?
SELECT COUNT("Enrollment") FROM table_28404 WHERE "Joined" = '1931, 1949 1'
SELECT COUNT("Enrollment") FROM "table_28404" WHERE "Joined" = '1931, 1949 1'