user: Question: When the Venue was MCG what was the sum of all Crowds for that venue?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Venue', 'Crowd', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['St Kilda', '14.16 (100)', 'South Melbourne', '13.15 (93)', 'Moorabbin Oval', 17454.0, '21 July 1973']
SQL:

assistant: SELECT SUM("Crowd") FROM "Table" WHERE "Venue" = 'MCG';