Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_15938543_1 (original_air_date VARCHAR, us_viewers__million_ VARCHAR)

### Question ###
How many episodes had an original air date with 5.1 million viewers

### Accurate SQL ###

SELECT COUNT(original_air_date) FROM table_15938543_1 WHERE us_viewers__million_ = "5.1"