Database: mental_health_survey
Question: How many users lived in Canada according to 2018's survey?
SQL: SELECT COUNT(T2.UserID) FROM Question AS T1 INNER JOIN Answer AS T2 ON T1.questionid = T2.QuestionID WHERE T2.SurveyID = 2018 AND T1.questiontext = 'What country do you live in?' AND T2.AnswerText = 'Canada'