What is the most common illness that doctors identified among the patients whose lab work was done between 1/1/1985, and 12/31/1995?
the most common illness refers to MAX(COUNT(Diagnosis)); lab work between 1/1/1985 and 12/31/1995 refers to `Examination Date` between '1985-01-01' and '1995-12-31 '
SELECT T2.Diagnosis FROM Examination AS T1 INNER JOIN Patient AS T2 ON T1.ID = T2.ID WHERE T1.`Examination Date` BETWEEN '1985-01-01' AND '1995-12-31' GROUP BY T2.Diagnosis ORDER BY COUNT(T2.Diagnosis) DESC LIMIT 1