CREATE TABLE table_26198709_1 (production_code VARCHAR, us_viewers__million_ VARCHAR)

What is the production code for the episode that had 18.07 million viewers?
SELECT production_code FROM table_26198709_1 WHERE us_viewers__million_ = "18.07"
SELECT "production_code" FROM "table_26198709_1" WHERE "18.07" = "us_viewers__million_"