What is to be explained?

In my last post, I said that the relationship between political views and happiness changed over time and that I'd have to think before offering an explanation.  My general idea was that political polarization had been growing, so that there was an increasing tendency for people to be less happy when the "wrong" party was in power.  The only problem was that there were signs of a growth in polarization in the 1990s, like the 1994 congressional election and the impeachment of Bill Clinton, so why wasn't anything visible then?  In the hope of getting a hint, I estimated the relationship between self-rated ideology and happiness by year, and got this:

Higher values mean a tendency for conservatives to be relatively less satisfied.  The zero value is arbitrary--it just represents the pattern in 2014.  The 95% confidence intervals for the annual estimates are about plus or minus .02 (about plus or minus .03 in the first half of the period), so you could not reject the hypothesis that all the values within the Bush or Obama presidencies were the same.  However, if you just look at the figure, it looks more like just random variation with a few exceptions--2004, 2008 and 2010.

So maybe the problem isn't to explain the patterns under recent presidents, but the patterns in a few particular years?  The GSS is conducted in March, and March 2010 was when the Affordable Care Act was passed.  So maybe that explains why conservatives (and especially "extremely conservative" people) were relatively unhappy then, but (maybe) not in 2012 and 2014.  With G. W. Bush, the 2002 pattern wasn't unusual, but 2004-8 were.  Those years had something in common--the United States was engaged in an extended war.  It seems plausible that liberals and moderates would be more worried about war and its implications.  The GSS started in 1972, but didn't include the question on political views until 1974, so being at war was a new event in the history of the available data (the first Gulf War took place in January/Feb 1991, but American troops were already leaving by March).

I'm not sure that what needs to be explained is a few unusual years rather than presidencies--the point is just that it's another way to look at it, and the data doesn't let us decide between the possibilities.  This is a case where we start with what seems like a lot of data--50,000 cases--which turns out to be a lot less than we need for some purposes.