22% of their GDP and 67% of exports are oil, they are extraordinarily exposed to changes in oil prices. All the oil wealth they funnel in to sovereign wealth funds, the largest of which is the public retirement fund which stands at over $700b. They are one of a very small number of countries which is not facing fiscal oblivion due to changing demographics, they have been extremely responsible with managing their surplus (in US budget speak its considered off-budget, oil income is not used to fund regular spending or offset taxes).
Interesting bit of history, thanks.
While I am sure that is true the tools we use to measure inequality don't allow us to see a particularly good picture. We have extraordinarily poor data for wealth & consumption inequality (the latter being the most important form) and traditional measures of income inequality suffer from a bias problem when one doesn't account for the uneven exposure to inflation between income groups, deficiencies in the way we measure income, deficiencies in the way we measure inflation etc.
The only reason I mentioned "Norway is more economically equal than the US" is to combat the inevitable, regurgitated reply of "using average is bad! You should use median!". If Norway is indeed more economically equal than the US then the difference between median incomes would likely be even bigger than the difference between mean incomes. But this isn't important.
Disposable income in the US is about 50% higher then in Norway. They don't publish data on discretionary income but given their PPP I would be very surprised if it changed their ranked position upwards vs disposable income. Adjusted median household income (usual warning regarding household income being a misleading metric when considering income) is ~8% lower then the US. Median wage is either 11% or 23% lower then the US depending on which BLS survey you use.
I am highly suspicious of these figures. The question specifically stated nominal wages, are you sure you're not getting confused and using PPP-adjusted figures?