user: Question: How many rankings were there for the season with a finale on August 20, 2011?
Columns: ['Season', 'Episodes', 'Timeslot (ET)', 'Season Premiere', 'Season Finale', 'TV Season', 'Rank', 'Viewers (in millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 10.0, 'Saturday 8:00 PM', 'February 21, 2004', 'August 14, 2004', '2003-2004', '#123', '6.21']
SQL:

assistant: SELECT COUNT("Rank") FROM "Table" WHERE "Season Finale" = 'August 20, 2011';