CREATE TABLE table_23851574_2 (aper_in VARCHAR2, built_used VARCHAR2)

Which aperture were built or used between 1987-2001?
SELECT aper_in FROM table_23851574_2 WHERE built_used = "1987-2001"
SELECT "aper_in" FROM "table_23851574_2" WHERE "1987-2001" = "built_used"