Calculate the increment percentage of elite user for each year since year 2005.
since year 2005 refers to year_id Between 2005 and 2014; increment percentage = Divide(Count(user_id(year_id < 2014)), Count (user_id(year_id = 2015))) * 100
SELECT CAST(COUNT(CASE WHEN year_id < 2014 THEN 1 ELSE NULL END) AS REAL) * 100 / COUNT(CASE WHEN year_id = 2005 THEN 1.0 ELSE NULL END) AS increment FROM Elite