user: Question: Name the viewers for 520
Columns: ['No. by series', 'No. by season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production number', 'U.S. viewers (in millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: [82.0, 1.0, '"After the Storm"', 'Rob Bowman', 'David Amann', 'September24,2012', 501.0, '10.45']
SQL:

assistant: SELECT "U.S. viewers (in millions)" FROM "Table" WHERE "Production number" = 520.0;