user: Question: What is every year for joined with the Ravens nickname?
Columns: ['Institution', 'Location', 'Founded', 'Type', 'Enrollment', 'Nickname', 'Joined']
Types: ['text', 'text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['Avila University', 'Kansas City, Missouri', 1916.0, 'Private / Catholic', 1939.0, 'Eagles', '2000']
SQL:

assistant: SELECT "Joined" FROM "Table" WHERE "Nickname" = 'Ravens';