CREATE TABLE table_49216 ("Year" FLOAT, "Team" TEXT, "Co-Drivers" TEXT, "Class" TEXT, "Laps" FLOAT, "Pos." TEXT, "Class Pos." TEXT)

What was the year of the finish with the class pos of 6th and laps smaller than 317?
SELECT SUM("Year") FROM table_49216 WHERE "Class Pos." = '6th' AND "Laps" < '317'
SELECT SUM("Year") FROM "table_49216" WHERE "Class Pos." = '6th' AND "Laps" < '317'