The Misery Index is the sum of the unemployment rate and the inflation rate. It can be found here: http://www.miseryindex.us/default.aspx
I figured taxes are pretty miserable, too, so I included federal taxes as a percent of GDP. It's a lot less volatile than the Misery Index because when unemployment increases, tax confiscations drop. The way I see it, rather than masking booms and hiding busts, it exposes persistent government induced misery that is otherwise masked during booms by the original Misery Index.
I figure there will be widespread rioting if it hits 50. Also, the Nixon-Carter years were really bad times.