CREATE TABLE table_17758010_2 (original_air_date VARCHAR, us_viewers__millions_ VARCHAR)

How many original air dates have U.S. Views (millions) of 19.49?
SELECT COUNT(original_air_date) FROM table_17758010_2 WHERE us_viewers__millions_ = "19.49"
SELECT COUNT("original_air_date") FROM "table_17758010_2" WHERE "19.49" = "us_viewers__millions_"