CREATE TABLE table_35306 ("Date" TEXT, "Tournament" TEXT, "Winning score" TEXT, "Margin of victory" TEXT, "Runner ( s ) -up" TEXT)

Which Date has a Margin of victory of 4 strokes?
SELECT "Date" FROM table_35306 WHERE "Margin of victory" = '4 strokes'
SELECT "Date" FROM "table_35306" WHERE "Margin of victory" = '4 strokes'