CREATE TABLE table_11981 ("Airing date" CLOB, "English title  ( Chinese title ) " CLOB, "Number of episodes" FLOAT, "HD format" CLOB, "Highest average point ratings" FLOAT, "Genre" CLOB, "Official website" CLOB)

What was the highest average point rating for a modern suspense show with 21 episodes?
SELECT SUM("Highest average point ratings") FROM table_11981 WHERE "Genre" = 'modern suspense' AND "Number of episodes" = '21'
SELECT SUM("Highest average point ratings") FROM "table_11981" WHERE "Genre" = 'modern suspense' AND "Number of episodes" = '21'