CREATE TABLE table_57100 ("Pos." FLOAT, "Driver" TEXT, "Time" TEXT, "Best time" TEXT, "Points" FLOAT)

What position is associated with a Time of 20:39.171?
SELECT AVG("Pos.") FROM table_57100 WHERE "Time" = '20:39.171'
SELECT AVG("Pos.") FROM "table_57100" WHERE "Time" = '20:39.171'