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