user: Question: What is the transfer fee for the MLI player with fewer than 63 goals in a year more recent than 2006?
Columns: ['Nat.', 'Name', 'Since', 'Goals', 'Ends', 'Transfer fee']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['ESP', 'Iker Casillas ( VC )', '1999', 0.0, '2017', 'Youth system']
SQL:

assistant: SELECT "Transfer fee" FROM "Table" WHERE "Since" = '2006' AND "Goals" < 63.0 AND "Nat." = 'MLI';