How about general public interest. Below is a graph of changes over time:
As you can see above, political interest increased during the 1960s and then dropped thanks to a Watergate effect in the 1970s and into the 1980s. It's remained largely constant, with a bit of a random walk year to year, really since about 1980. So we can't argue that the public's interest has waned. Then again, it's not all that high either. These are the folks who responded with very high interest and the numbers sit about one-quarter of U.S. adults.
Okay, how about trust? Glad you asked.
Trust dropped significantly during the 1960s (Vietnam, race) and the 1970s (Watergate), inched up in the 1980s (Reagan, Morning in America), dropped again in 1994 (GOP takeover), began a nice increase during the 1990s and 2000s and then dropped like a rock in recent years (the Obama effect?). You can come up with any number of other explanations for these shifts up and down and all around, but my favorite would probably be that pounding against government, from left or right, along with real-world events combine to damage the nation's reputation with the public.
Another concept we're often interested in is efficacy. That is, do people think they can make a difference. The graph below captures that by flipping the data to describe those who do think they can have an effect on politics.
As you can see above, the question has to do with politics being "too complicated" for one to understand. These are the "disagree" folks above, so they represent people who feel they can understand and make a difference. The proportion of these folks decreased during the same period that trust went down, but then remained relatively steady until recent years when there's a bit of a jumping up and down. Smoothing the data by looking only at presidential election years takes some of this randomness out. In general, efficacy seems to be slightly decreasing of late.
What all this mean? Recent years both look a lot like previous ones but there are also significant changes. If you go to the site, linked above, and play with graphs you can see for yourself across any number of variables and concepts, from attitudes about specific issues to voting. A lot of useful stuff here.