CREATE TABLE table_9439 ("Institution" TEXT, "Location" TEXT, "Founded" FLOAT, "Affiliation" TEXT, "Enrollment" FLOAT, "Team Nickname" TEXT)

what is the least enrollment when founded after 1809 and the institution is university of michigan?
SELECT MIN("Enrollment") FROM table_9439 WHERE "Founded" > '1809' AND "Institution" = 'university of michigan'
SELECT MIN("Enrollment") FROM "table_9439" WHERE "Founded" > '1809' AND "Institution" = 'university of michigan'