CREATE TABLE table_64586 ("Tournament" TEXT, "2000" TEXT, "1999" TEXT, "1998" TEXT, "1997" TEXT, "1996" TEXT, "1995" TEXT, "1994" TEXT, "1993" TEXT, "1992" TEXT, "1991" TEXT)

What is the 1991 when 1997 is 18?
SELECT "1991" FROM table_64586 WHERE "1997" = '18'
SELECT "1991" FROM "table_64586" WHERE "1997" = '18'