I asked to leave Sweden out... the exactly who of the discussion is not important.
I'll put something out there for consideration.
In the Gulf War, the US committed troops because it wanted to. In all other instances you are referring to, it probably wanted to as well. I think its possible that if the US didn't want to commit troops, that it wouldn't, regardless of whether the UN needed it or not.
In other words, I think its possible that the commitment of troops is independent of the UN view, and is entirely related to US self-interest. Historically, the UN view and the US view have been in accord. Therefore, it might appear that the US contributes troops at the whim of the UN, but that may not be the case.
As distinct from the giving of aid, which the UN agreed at a level of GNI and the US has under-contributed (as a percentage of GNI), compared to its peers.
I have absolutely no idea whether the amount the US did contribute is actually fair or not (it sure is a lot of money). And it doesn't really matter. The entire point is that Jorge implied that the US is doing more as an international citizen than other countries, when on an income basis it is arguably doing less.
(edit) I am also unlikely to be able to find a nice table of the relative contributions of the Gulf War. I wish I could. I am interested now. Note - best I can do:
http://www.cryan.com/war/AlliedForces.html
Financially, looks like the US (at $9b) put in less than Japan and Germay combined (at $16b) (bottom of page):
http://www.cnn.com/SPECIALS/2001/gulf.war/facts/gulfwar/