user: Question: what is the least enrollment when founded after 1809 and the institution is University of Michigan?
Columns: ['Institution', 'Location', 'Founded', 'Affiliation', 'Enrollment', 'Team Nickname']
Types: ['text', 'text', 'real', 'text', 'real', 'text']
Sample row: ['Ferris State University', 'Big Rapids, Michigan', 1884.0, 'Public', 13532.0, 'Bulldogs']
SQL:

assistant: SELECT MIN("Enrollment") FROM "Table" WHERE "Founded" > 1809.0 AND "Institution" = 'University of Michigan';