user: Question: How many viewers (millions) were there for rank (week) 20?
Columns: ['#', 'Episode', 'Rating', 'Share', 'Rating/Share (18-49)', 'Viewers (millions)', 'Rank (timeslot)', 'Rank (night)', 'Rank (week)']
Types: ['real', 'text', 'text', 'real', 'text', 'text', 'real', 'real', 'text']
Sample row: [1.0, '"Pilot"', '7.1', 12.0, '3.8/9', '10.72', 2.0, 8.0, '20']
SQL:

assistant: SELECT "Viewers (millions)" FROM "Table" WHERE "Rank (week)" = '20';