How many black patients stopped their care plan in 2017?
black refers to race = 'black'; stopped their care plan in 2017 refers to substr(careplans.STOP, 1, 4) = '2017';
SELECT COUNT(DISTINCT T2.patient) FROM careplans AS T1 INNER JOIN patients AS T2 ON T1.PATIENT = T2.patient WHERE T2.race = 'black' AND strftime('%Y', T1.STOP) = '2017'