CREATE TABLE table_79914 ("Name" TEXT, "Street address" TEXT, "Years as tallest" TEXT, "Height feet / m" TEXT, "Floors" FLOAT)

How many years was the building with 24 floors the tallest?
SELECT "Years as tallest" FROM table_79914 WHERE "Floors" = '24'
SELECT "Years as tallest" FROM "table_79914" WHERE "Floors" = '24'