CREATE TABLE table_64189 ("2005/ 06" TEXT, "2006/ 07" TEXT, "2007/ 08" TEXT, "2009/ 10" TEXT, "2010/ 11" TEXT, "2011/ 12" TEXT, "2012/ 13" TEXT)

Which 2005/ 06 has a 2011/ 12 of ranking tournaments
SELECT "2005/ 06" FROM table_64189 WHERE "2011/ 12" = 'ranking tournaments'
SELECT "2005/ 06" FROM "table_64189" WHERE "2011/ 12" = 'ranking tournaments'