user: Question: What is the average round of a player with an overall of 138?
Columns: ['Round', 'Overall', 'Player', 'Position', 'Nationality', 'Club team']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '17', 'Curtis Lazar', 'Centre/Right Wing', 'Canada', 'Edmonton Oil Kings (WHL)']
SQL:

assistant: SELECT AVG("Round") FROM "Table" WHERE "Overall" = '138';