CREATE TABLE table_42496 ("Year" FLOAT, "Winner" TEXT, "School" TEXT, "Position" TEXT, "Points" TEXT, "% of Points Possible" TEXT)

What is the total year of the winner who plays the halfback position with a % of points possible of 80.64%?
SELECT COUNT("Year") FROM table_42496 WHERE "Position" = 'halfback' AND "% of Points Possible" = '80.64%'
SELECT COUNT("Year") FROM "table_42496" WHERE "% of Points Possible" = '80.64%' AND "Position" = 'halfback'