user: Question: When was the season finale that ranked 20th?
Columns: ['Season', 'Episodes', 'Timeslot ( EST )', 'Season premiere', 'Season finale', 'TV season', 'Rank', 'Viewers (in millions)']
Types: ['text', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1st', 23.0, 'Tuesday 8:00PM', 'September 23, 2003', 'May 25, 2004', '2003–04', '26th', '11.84']
SQL:

assistant: SELECT "Season finale" FROM "Table" WHERE "Rank" = '20th';