CREATE TABLE table_22078972_2 (title VARCHAR, us_viewers__millions_ VARCHAR)

What's the title of the episode first seen by 18.15 million people in the US?
SELECT title FROM table_22078972_2 WHERE us_viewers__millions_ = "18.15"
SELECT "title" FROM "table_22078972_2" WHERE "18.15" = "us_viewers__millions_"