user: Question: What is the average number of not usable satellited when there are 0 retired, and the launch failures are less than 1?
Columns: ['Block', 'Launched', 'Operational', 'Not usable', 'Retired', 'Launch Failures']
Types: ['text', 'real', 'real', 'real', 'real', 'real']
Sample row: ['Block I', 11.0, 0.0, 0.0, 10.0, 1.0]
SQL:

assistant: SELECT AVG("Not usable") FROM "Table" WHERE "Retired" = 0.0 AND "Launch Failures" < 1.0;