These two cities of the US have the highest GDPs.
I have framed this sentence. I would like to know if the word GDP should be plural here, since we are talking about two different GDPs of two different cities, and I have really not come across the word GDPs ever. Should it be GDP or GDPs?
[Note: This question is still unanswered. I am looking forward to getting an answer which addresses the actual problem.]