CREATE TABLE table_16757 ("#" FLOAT, "Race Name" TEXT, "Circuit" TEXT, "Date" TEXT, "Winning driver" TEXT, "Constructor" TEXT, "Report" TEXT)

How many constructors are listed for the XVI BRDC international trophy race
SELECT COUNT("Constructor") FROM table_16757 WHERE "Race Name" = 'XVI BRDC International Trophy'
SELECT COUNT("Constructor") FROM "table_16757" WHERE "Race Name" = 'XVI BRDC International Trophy'