I like FSI, which is a dimensionless number taking into account basically the functioning of society and the likelihood for unrest. (Fragile State Index)

It's the highest, at the moment, that it's been since the 1800s. The nadir for the US was in the late 40s early 50s when we had a 92% top marginal tax rate and extremely high social cohesion despite massive WW2 debts. Needless to say the late 40s and early 50s was not exactly utopia, but substantially more stable.