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_27012 ( "Vehicle" text, "Operating mode" text, "EPA rated All-electric range" text, "EPA rated combined fuel economy" text, "Clean electric grid California (San Francisco)" text, "U.S. national average electric mix" text, "Dirty electric grid Rocky Mountains (Denver)" text )

### Question ###
When 380 g/mi (236 g/km) is the dirty electric grid rocky mountains (denver) what is the u.s national average electric mix?

### Accurate SQL ###

SELECT "U.S. national average electric mix" FROM table_27012 WHERE "Dirty electric grid Rocky Mountains (Denver)" = '380 g/mi (236 g/km)'