CREATE TABLE table_35788 ("Name" TEXT, "City" TEXT, "Years as tallest" TEXT, "Metres" FLOAT, "Feet" FLOAT, "Floors" FLOAT)

What is listed under the Years as tallest, that has Floors of 31?
SELECT "Years as tallest" FROM table_35788 WHERE "Floors" = '31'
SELECT "Years as tallest" FROM "table_35788" WHERE "Floors" = '31'