How many American drivers have been disqualified from the race.
disqualified refers to statusID = 2;
SELECT COUNT(T1.driverId) FROM drivers AS T1 INNER JOIN results AS T2 on T1.driverId = T2.driverId INNER JOIN status AS T3 on T2.statusId = T3.statusId WHERE T3.status = 2 AND T1.nationality = 'American'