user: Question: What was the size of the crowd when the away team scored 6.15 (51)?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Venue', 'Crowd', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['Hawthorn', '15.13 (103)', 'South Melbourne', '6.15 (51)', 'Glenferrie Oval', 11000.0, '11 July 1964']
SQL:

assistant: SELECT "Crowd" FROM "Table" WHERE "Away team score" = '6.15 (51)';