Calculate the average period of Mr. Wesley Lemke's care plans.
DIVIDE(SUBTRACT(stop time - start time), COUNT(ID)));
SELECT CAST(SUM(strftime('%J', T2.STOP) - strftime('%J', T2.START)) AS REAL) / COUNT(T1.patient) FROM patients AS T1 INNER JOIN careplans AS T2 ON T1.patient = T2.PATIENT WHERE T1.prefix = 'Mr.' AND T1.first = 'Wesley' AND T1.last = 'Lemke'