user: Question: What is the average amount of floors of the building that is ranked larger than 30, a year prior to 1977 and an address of 100 Van Ness Avenue?
Columns: ['Rank', 'Name', 'Height ft (m)', 'Floors', 'Year']
Types: ['real', 'text', 'text', 'real', 'real']
Sample row: [1.0, 'Transamerica Pyramid', '853 (260)', 48.0, 1972.0]
SQL:

assistant: SELECT AVG("Floors") FROM "Table" WHERE "Rank" > 30.0 AND "Year" < 1977.0 AND "Name" = '100 Van Ness Avenue';