CREATE TABLE table_2866503_1 (us_air_date VARCHAR2, us_viewers__million_ VARCHAR2)

What is the U.S. air date when the U.S. viewers are 7.5 million?
SELECT us_air_date FROM table_2866503_1 WHERE us_viewers__million_ = "7.5"
SELECT "us_air_date" FROM "table_2866503_1" WHERE "7.5" = "us_viewers__million_"