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_20553 ( "Vehicle" text, "EPA rated All-electric range" text, "EPA rated combined fuel economy" text, "Alaska ( Juneau )" text, "California (San Francisco)" text, "Mid-Atlantic South (Washington, D.C.)" text, "U.S. national average electric mix" text, "Southeast (Atlanta)" text, "Midwest (Des Moines)" text, "Rocky Mountains (Denver)" text )

### Question ###
What was the US national average electric mix rating for the vehicle that was rated 280 g/mi (174 g/km) in the Midwest?

### Accurate SQL ###

SELECT "U.S. national average electric mix" FROM table_20553 WHERE "Midwest (Des Moines)" = '280 g/mi (174 g/km)'