It's been awhile since I looked at these stats but as of like 2008 more people identified as Republican than Democrat.
https://www.washingtonpost.com/news/politics/wp/2018/07/24/o...
PS: It’s also irrelevant as many people identify as independents while actually voting overwhelmingly for a single party. Further, political power has nothing to do with the national popular vote let alone what the non voting public believes. For example Trump won with 46.1% of the popular vote and votes from about 19.5% of the total population. That’s simply how the system works and what shapes politics.
My guess is it’s a difference between stated preferences and actual preferences.