user: Question: What is the goal difference number with a position of 15?
Columns: ['Position', 'Team', 'Played', 'Drawn', 'Lost', 'Goals For', 'Goals Against', 'Goal Difference', 'Points 1']
Types: ['real', 'text', 'real', 'real', 'real', 'real', 'real', 'text', 'text']
Sample row: [1.0, 'Kirkby Town', 34.0, 5.0, 3.0, 83.0, 30.0, '+53', '57']
SQL:

assistant: SELECT "Goal Difference" FROM "Table" WHERE "Position" = 15.0;