Among the coaches who have taught teams from the NHL League, how many of them are from Canada?
from Canada refers to birthCountry = 'Canada'; NHL league refers to lgID = 'NHL'
SELECT COUNT(T2.coachID) FROM Master AS T1 INNER JOIN Coaches AS T2 ON T1.coachID = T2.coachID WHERE T2.lgID = 'NHL' AND T1.birthCountry = 'Canada'