user: Question: When there are 5.2 million u.s. viewers how many numbers in series are there?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (millions)']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['51', '1', '" iThink They Kissed "', 'Adam Weissman', 'Steve Holland', 'September12,2009', '227', '7.6']
SQL:

assistant: SELECT COUNT("No. in series") FROM "Table" WHERE "U.S. viewers (millions)" = '5.2';