According to 2016's survey, what is the number of users with a mental health disorder in the past?
users with a mental health disorder in the past refers to AnswerText(QuestionID(32)) = 'Yes'
SELECT COUNT(T2.UserID) FROM Question AS T1 INNER JOIN Answer AS T2 ON T1.questionid = T2.QuestionID WHERE T2.SurveyID = 2016 AND T1.questiontext LIKE 'Have you had a mental health disorder in the past?' AND T2.AnswerText = 'Yes'
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, 
