Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_68776 ( "Name" text, "Street Address" text, "Years as tallest" text, "Height ft / m" text, "Floors" real )

### Question ###
During what years did the tallest building, located at 211 Union Street, have less than 31 floors?

### Accurate SQL ###

SELECT "Years as tallest" FROM table_68776 WHERE "Floors" < '31' AND "Street Address" = '211 union street'