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_10007452_3 ( fleet_series__quantity_ VARCHAR, fuel_propulsion VARCHAR )

### Question ###
how many times is the fuel propulsion is cng?

### Accurate SQL ###

SELECT COUNT(fleet_series__quantity_) FROM table_10007452_3 WHERE fuel_propulsion = "CNG"