I felt compelled to look this up today.
The U.S. accounts for more than 48 percent of all defense spending in the entire world, if you take into account the costs of the Iraq and Afghanistan wars and the cost of maintaining nuclear weapons, which is not paid for by the military (who knew?).
In 2008, the whole world spent $1.43 trillion on military stuff. The U.S. spends $711 billion of that.
If you add up our spending and that of our NATO allies, that comes to something like 72 percent of all military spending on the planet.
I also wanted to look this up:
The U.S. operates about two thirds of all the aircraft carriers in the world. We have 12 active super-carriers (with at least two more inactive but fit to recommission quickly), plus at least 10 of the smaller amphibious assault ships, which are effectively aircraft carriers. Even using a fairly generous definition of "aircraft carrier", there are only 13 active non-American carriers on the whole planet and only England and France have more than one (the Royal Navy has four, the French have two).
This leaves me with an important question:
Shouldn't we be kicking butt somewhere or something?