SELECT "Rd." FROM table_16639 WHERE "Grand Prix" = 'Canadian Grand Prix'
What number is the Canadian Grand Prix on the list?
CREATE TABLE table_16639 (
    "Rd." real,
    "Grand Prix" text,
    "Pole Position" text,
    "Fastest Lap" text,
    "Winning Driver" text,
    "Constructor" text,
    "Report" text
)