The decline of serious reading is associated with the loss of freedom in America. People don't understand the gift they were given when the founders created a new form of government--the constitutional republic. Ann Coulter has addressed the problem of Republicans who don't read. I am sure there are plenty of nonreaders among Democrats as well. My educated guess would be that Libertarians probably read the most (just quiz them on the Constitution, Federalist Papers, or anything related to freedom and you'll be impressed!) and the non-affiliated read the least (that's why they think "all parties are the same.")
I'm afraid Ann is right about nonreaders. That's why nobody knows the historical record of Marxism, appeasement, disarmament, and religious intolerance. That's why people think the government can fix everything and take care of them. That's why they don't even know what's in the Constitution that was written to protect them FROM the government. Most of them no longer even understand that they NEED protection from the government. That's how freedom dies--through ignorance and laziness.
If you are reading this, I'm hoping that makes you a serious reader. May I suggest the following:
Modern Times by Paul Johnson for a bloody history of the twentieth century. Give a copy of this book to your Marxist acquaintances and defy them to defend the historical record of their deadly philosophy!
Economics in One Lesson by Henry Hazlitt is economics for the math-anxious. Understand the concepts without doing regression analysis.
The Antitrust Paradox by Robert Bork is an excellent, detailed study of just one of the failures of progressivism--a perfect example of good intentions that have bad consequences.