user: Question: What is the completion percentage when yards per attempt was done by Steve McNair : 2003?
Columns: ['Rank', 'Rating', 'Completion Percentage', 'Touchdown Percentage', 'Yards Per Attempt', 'Total Yards']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1', '158.3', '83.3%', '21.9%', '18.6', '554']
SQL:

assistant: SELECT "Completion Percentage" FROM "Table" WHERE "Yards Per Attempt" = 'Steve McNair : 2003';