Mr./Ms. Statistics,
You are obviously a bright person, so I will try once more.
Your explanation justifies and explains your assumptions pretty well, but misses my point somewhat.
Fox is a dissenting point of view. Using your numbers, 12 million people see it at some point in the day. 296 million people don't. That dissenting point of view is a counterpoint to decades of left leaning media bias, a bias which is well disseminated throughout society, without people having to turn to the media on any given day to acquire it. It's a bias that permeates U.S. education, workplaces, and movies, etc.
If the left biased media hadn't been so predominant for decades, your percentage calculation would have more validity. By analogy, think of a soaking rain in a field for a month. Then, on the first day of the new month, forty percent of the rain that comes down is captured in a container. The measure of the water in the field is most certainly not just the sixty percent the container did not capture on that day. The measure of what is in the container is just a small part of the whole.
Fox News is an affront to those who see a version of the news with a liberal slant made popular by a couple of decades of orthodoxy on the affairs of the day. Some now greedily call that slanted reporting "history," trying to enshrine a point of view as immutable truth.
Fortunately, that will be sorted out over time. Fox irritates the left, but more telling is the presence of dissenting views on the internet. A generation of curious young people now have regular exposure to alternative points of view, beyond that fed to them in school, or by those around them, or through the news media. I think that Fox is a small part of the sea change that is coming, made possible once people find out that the complained of "bias," now alleged against Fox News is just a different one, and a new one, with a much larger and longstanding bias of the left that was designed to permeate the dissemination of news, education, and entertainment.
Oh, for what it's worth, I watched Fox News Channel for less than an hour total in 2010. With the internet, the evening news is a slow and delayed review of what I already learned earlier in the day. I watch MSNBC programs such as Olbermann and Maddow for their point of view about once per week, as sometimes, they are very enlightening. They have a bias, but they can be very good in reporting on things others ignore.
Thanks again for your contribution of substituting daily viewing totals for program ones. It's a very valid and basic point that I missed initially.