user: Question: How many U.S. air dates were from an episode in Season 4?
Columns: ['No. in season', 'No. in series', 'Title', 'Canadian airdate', 'US airdate', 'Production code']
Types: ['real', 'real', 'text', 'text', 'text', 'real']
Sample row: [1.0, 144.0, '"Uptown Girl" Part One', '5 October 2008', '10 October 2008', 801.0]
SQL:

assistant: SELECT COUNT("US airdate") FROM "Table" WHERE "No. in season" = 4.0;