CREATE TABLE table_38670 ("Year" FLOAT, "Class" TEXT, "Team" TEXT, "Points" FLOAT, "Rank" TEXT, "Wins" FLOAT)

What is the earliest year with less than 45 points for Yamaha team in 21st rank?
SELECT MIN("Year") FROM table_38670 WHERE "Points" < '45' AND "Team" = 'yamaha' AND "Rank" = '21st'
SELECT MIN("Year") FROM "table_38670" WHERE "Points" < '45' AND "Rank" = '21st' AND "Team" = 'yamaha'