Database: thrombosis_prediction
Question: For the patient who was born on 1959/2/18, what is the decrease rate for his/her total cholesterol from November to December in 1981?
SQL: SELECT CAST((SUM(CASE WHEN T2.Date LIKE '1981-11-%' THEN T2.`T-CHO` ELSE 0 END) - SUM(CASE WHEN T2.Date LIKE '1981-12-%' THEN T2.`T-CHO` ELSE 0 END)) AS REAL) / SUM(CASE WHEN T2.Date LIKE '1981-12-%' THEN T2.`T-CHO` ELSE 0 END) FROM Patient AS T1 INNER JOIN Laboratory AS T2 ON T1.ID = T2.ID WHERE T1.Birthday = '1959-02-18'