user: Question: During what years did the tallest building, located at 211 Union Street, have less than 31 floors?
Columns: ['Name', 'Street Address', 'Years as tallest', 'Height ft / m', 'Floors']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['First National Bank Building', '170 Fourth Avenue North', '1905–1908', '170 / 52', 12.0]
SQL:

assistant: SELECT "Years as tallest" FROM "Table" WHERE "Floors" < 31.0 AND "Street Address" = '211 Union Street';