CREATE TABLE table_16431 ("Rnd" FLOAT, "Race Name" CLOB, "Pole position" CLOB, "Fastest lap" CLOB, "Winning driver" CLOB, "Winning team" CLOB, "Report" CLOB)

In Round 6, how many winning drivers were there?
SELECT COUNT("Winning driver") FROM table_16431 WHERE "Rnd" = '6'
SELECT COUNT("Winning driver") FROM "table_16431" WHERE "Rnd" = '6'