user: Question: How many share figures are there for the episode that aired on October 17, 2007?
Columns: ['#', 'Episode', 'Air Date', 'Timeslot (EST)', 'Rating', 'Share', '18-49 (Rating/Share)', 'Viewers (m)', 'Weekly Rank (#)']
Types: ['real', 'text', 'text', 'text', 'text', 'real', 'text', 'text', 'real']
Sample row: [2.0, '"In Which Sam Receives an Unexpected Visitor"', 'October 3, 2007', 'Wednesday 9:00 P.M.', '8.3', 13.0, '4.3/13', '12.3', 17.0]
SQL:

assistant: SELECT COUNT("Share") FROM "Table" WHERE "Air Date" = 'October 17, 2007';