TV Ratings is a really poor term. For example, I would not be counted in TV ratings, but I watched the Superbowl.
Then you have that ratings are a percentage, not a straight up number. So 10% of LA watching might be more people than 40% of Cincinnati. This is also based on roughly 21,000 households that are monitored out of something like 127 million people who have TVs in their home.
Also, when you dig into how Nielsen accounts for viewership and then viewership outside of the home (February in Cincinnati and LA are two very different things), these ratings are basically massive guesses.