CREATE TABLE table_203_539 (id DECIMAL, "year" DECIMAL, "competition" TEXT, "venue" TEXT, "position" TEXT, "event" TEXT, "notes" DECIMAL)

how many 110 m hurdles did china compete in ?
SELECT COUNT(*) FROM table_203_539 WHERE "event" = '110 m hurdles'
SELECT COUNT(*) FROM "table_203_539" WHERE "event" = '110 m hurdles'