user: Question: What's the average round the position of RB was drafted?
Columns: ['Round', 'Pick', 'Name', 'Position', 'College']
Types: ['real', 'real', 'text', 'text', 'text']
Sample row: [1.0, 28.0, 'Lawrence Jackson', 'DE', 'USC']
SQL:

assistant: SELECT AVG("Round") FROM "Table" WHERE "Position" = 'RB';