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

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'