List down application that have not been updated since 2015. What is the percentage of this application having more negative sentiment than positive sentiment?
percentage = DIVIDE(SUBTRACT(SUM(Sentiment = 'Positive')), (SUM(Sentiment = 'Negative'))), (SUM(Sentiment = 'Negative')) as percent; Last Updated>'2015';
SELECT CAST((( SELECT COUNT(*) Po FROM playstore AS T1 INNER JOIN user_reviews AS T2 ON T1.App = T2.App WHERE SUBSTR(T1."Last Updated", -4, 4) > '2015' AND T2.Sentiment = 'Positive' ) - ( SELECT COUNT(*) Ne FROM playstore AS T1 INNER JOIN user_reviews AS T2 ON T1.App = T2.App WHERE SUBSTR(T1."Last Updated", -4, 4) > '2015' AND T2.Sentiment = 'Negative' )) AS REAL) * 100 / ( SELECT COUNT(*) NUM FROM playstore AS T1 INNER JOIN user_reviews AS T2 ON T1.App = T2.App WHERE SUBSTR(T1."Last Updated", -4, 4) > '2015' )
database name:db_id app_store
googleplaystore table googleplaystore Cols: App dtype text, Category dtype text, Rating dtype real, Reviews dtype integer, Size dtype text, Installs dtype text, Type dtype text, Price dtype text, Content Rating dtype text, Genres dtype text, 
googleplaystore_user_reviews table googleplaystore_user_reviews Cols: App dtype text, Translated_Review dtype text, Sentiment dtype text, Sentiment Polarity dtype text, Sentiment Subjectivity dtype text, 
