47025
Air combat over North Vietnam between 1965 and 1973 led to an overall exchange ratio ( ratio of enemy aircraft shot down to the number of own aircraft lost to enemy fighters ) of 2.2 : 1 .
 North Vietnam
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 North Vietnam