user: Question: What is the average Total when silver is less than 1, and the rank is 15?
Columns: ['Rank', 'Nation', 'Gold', 'Silver', 'Bronze', 'Total']
Types: ['text', 'text', 'real', 'real', 'real', 'real']
Sample row: ['1', 'Soviet Union', 11.0, 2.0, 4.0, 17.0]
SQL:

assistant: SELECT AVG("Total") FROM "Table" WHERE "Silver" < 1.0 AND "Rank" = '15';