Betweeen 2016 to 2019, which year recorded the highest number of people with mental illness?
Between 2016 to 2019 refer to SurveyID 2016 BETWEEN 2019; People with mental illness refers to AnswerText = 'Yes' where questionid = 34
SELECT T1.SurveyID FROM Answer AS T1 INNER JOIN Question AS T2 ON T1.QuestionID = T2.questionid WHERE T1.SurveyID BETWEEN 2016 AND 2019 AND T2.questionid = 34 AND T1.AnswerText LIKE 'Yes' GROUP BY T1.SurveyID ORDER BY COUNT(T1.UserID) DESC LIMIT 1
database name:db_id mental_health_survey
Question table Question Cols: question text dtype text, question id dtype integer, 
Survey table Survey Cols: Survey ID dtype integer, Description dtype text, 
Answer table Answer Cols: Answer Text dtype text, Survey ID dtype integer, User ID dtype integer, Question ID dtype integer, 
