CREATE TABLE table_26305 ("No." FLOAT, "Episode" TEXT, "Rating" TEXT, "Share" FLOAT, "Rating/share  ( 18-49 ) " TEXT, "Viewers  ( millions ) " TEXT, "Rank  ( timeslot ) " FLOAT, "Rank  ( night ) " FLOAT)

What was the rating/share for 18-49 for the episode that had 5.90 million viewers?
SELECT "Rating/share (18-49)" FROM table_26305 WHERE "Viewers (millions)" = '5.90'
SELECT "Rating/share (18-49)" FROM "table_26305" WHERE "Viewers (millions)" = '5.90'