user: Question: What is the sum of Year(s), when Postion is 6th, and when Competition is Commonwealth Games?
Columns: ['Year', 'Competition', 'Venue', 'Position', 'Event']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [2000.0, 'Oceania Youth Championships', 'Adelaide , Australia', '1st', 'Javelin']
SQL:

assistant: SELECT SUM("Year") FROM "Table" WHERE "Position" = '6th' AND "Competition" = 'Commonwealth Games';