user: Question: What's the average mph of 1964?
Columns: ['Year', 'Date', 'Driver', 'Team', 'Manufacturer', 'Laps', 'Miles (km)', 'Race Time', 'Average Speed (mph)', 'Report']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1960', 'October 30', 'Bobby Johns', 'Cotton Owens', 'Pontiac', '334', '501 (806.281)', '4:36:44', '108.408', 'Report']
SQL:

assistant: SELECT "Average Speed (mph)" FROM "Table" WHERE "Year" = '1964';