How many users believed that their productivity is ever affected by a mental health issue overall?
Users who believed that their productivity is affected by a mental health issues overall refers to AnswerText = 'Yes' where questionid = 54
SELECT COUNT(T1.UserID) FROM Answer AS T1 INNER JOIN Question AS T2 ON T1.QuestionID = T2.questionid WHERE T2.questionid = 54 AND T1.AnswerText LIKE 'Yes'