user: Question: How many different numbers of people in the US who'd seen the episode with a season number 8 are there?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [23.0, 1.0, '" Manhunt "', 'Kevin Hooks', 'Paul Scheuring', 'August21,2006', '2AKJ01', '9.37']
SQL:

assistant: SELECT COUNT("U.S. viewers (millions)") FROM "Table" WHERE "No. in season" = 8.0;