The geographic/demographic map on the first page of the website posted below shows the distribution of people using the different terms: soda, pop, coke.
I tried to find the Freakonomics episode which featured this but my Google-foo talents were not up the match. I did find the sequence of whether your name could keep you from getting a job though! It was during the same show.

The Pop vs. Soda Page

In any case - the 'Coke' crowd was more widespread than I remembered.