user: Question: How many times did episode 17 originally air?
Columns: ['Episode No. Episode No. refers to the episodes number in the overall series, whereas Series No. refers to the episodes number in this particular series.', 'Series No.', 'Episode', 'Director', 'Writer(s)', 'Original airdate']
Types: ['real', 'real', 'text', 'text', 'text', 'text']
Sample row: [16.0, 1.0, '"A Little Lobbying"', 'Antonia Bird', 'Jeremy Brock and Paul Unwin', '12September1987']
SQL:

assistant: SELECT COUNT("Original airdate") FROM "Table" WHERE "Episode No. Episode No. refers to the episodes number in the overall series, whereas Series No. refers to the episodes number in this particular series." = 17.0;