CREATE TABLE table_2392 ("Episode" FLOAT, "First Air Date" TEXT, "Rating  ( 18\\u201349 ) " TEXT, "Share  ( 18\\u201349 ) " FLOAT, "Viewers  ( millions ) " TEXT, "Rank  ( timeslot ) " TEXT)

Name the total number for 18-49 share being 18-49 being 3.1
SELECT COUNT("Share (18\u201349)") FROM table_2392 WHERE "Rating (18\u201349)" = '3.1'
SELECT COUNT("Share (18\u201349)") FROM "table_2392" WHERE "Rating (18\u201349)" = '3.1'