What is the average number of respondents per survey between 2014 and 2019?
respondents and 'users' are synonyms; average number = avg(count(userID(SurveyID = 2014)), count(userID(SurveyID = 2019)))
SELECT CAST(COUNT(SurveyID) AS REAL) / 5 FROM Answer WHERE SurveyID BETWEEN 2014 AND 2019
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, 
