user: Question: How many series numbers are there when there were 15.8 u.s. viewers (millions)?
Columns: ['Series #', 'Season #', 'Title', 'Directed by', 'Written by', 'Original air date', 'U.S. viewers (millions)']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [93.0, '1', '"...And the Horse He Rode in On"', 'James Burrows', 'Adam Barr', 'September26,2002', '21.5']
SQL:

assistant: SELECT COUNT("Series #") FROM "Table" WHERE "U.S. viewers (millions)" = '15.8';