CREATE TABLE table_50782 ("Tournament" TEXT, "1990" TEXT, "1991" TEXT, "1992" TEXT, "1993" TEXT, "1994" TEXT, "1995" TEXT, "1996" TEXT, "1997" TEXT, "1998" TEXT, "1999" TEXT, "2000" TEXT, "2001" TEXT, "2002" TEXT, "2003" TEXT, "2004" TEXT, "2005" TEXT, "2006" TEXT, "2007" TEXT, "2008" TEXT)

What shows for 2006 when 1999 is Grand Slam Tournaments?
SELECT "2006" FROM table_50782 WHERE "1990" = 'grand slam tournaments'
SELECT "2006" FROM "table_50782" WHERE "1990" = 'grand slam tournaments'