Calculate the ratio in percentage between the average number of app users belonging to "80s Japanese comic" and "90s Japanese comic".
ratio in percentage = DIVIDE(SUM(IF(category = '80s Japanese comic',1,0)), COUNT(app_id)) as '80s'; DIVIDE(SUM(IF(category = '90s Japanese comic',1,0)), COUNT(app_id)) as '90s'; 80s Japanese comic refers to category = '80s Japanese comic'; 90s Japanese comic refers to category = '80s Japanese comic';
SELECT SUM(IIF(T1.category = '80s Japanese comic', 1, 0)) / COUNT(T1.label_id) AS J8 , SUM(IIF(T1.category = '90s Japanese comic', 1, 0)) / COUNT(T1.label_id) AS J9 FROM label_categories AS T1 INNER JOIN app_labels AS T2 ON T1.label_id = T2.label_id