CREATE TABLE table_20669 ("Year" FLOAT, "Dates" TEXT, "Champion" TEXT, "Country" TEXT, "Score" FLOAT, "To par" TEXT, "Margin of victory" TEXT, "Tournament location" TEXT, "Purse  (  US $  ) " FLOAT, "Winners share" TEXT)

Name the dates for margin of victory being 5 strokes
SELECT COUNT("Dates") FROM table_20669 WHERE "Margin of victory" = '5 strokes'
SELECT COUNT("Dates") FROM "table_20669" WHERE "Margin of victory" = '5 strokes'