SELECT YEAR(a.release_date), a.ranks, a.movie_name,
       ROUND(a.sale_amt / b. total_amt * 100, 2) percentage
  FROM box_office a
 INNER JOIN (SELECT YEAR(release_date) years, SUM(sale_amt) total_amt
               FROM box_office
              WHERE YEAR(release_date) >= 2015
              GROUP BY 1
             ) b
    ON YEAR(a.release_date) = b.years
 WHERE a.ranks <= 3
 ORDER BY 1, 2;