The US Defense Budget runs about four percent of Gross National Product (GNP) now as compared to ten percent GNP during Vietnam years.
Thus the burden the US Economy is carrying now is less than one half of that during the late '60's and early '70's.
The US economy's growth makes the major difference in the percentage number.
The other factor that has come to bear is the lack of procurement over the past decade or so as the result of the "peace benefit" after the end of the Cold War.
http://www.strategypage.com/dls/articles/2005919049.asp
Perhaps the "if it was good enough for Pershing crowd...." within the US Army had embraced change instead of fighting it....the Army would be in a much better condition today instead of where it is.
http://www.pbs.org/newshour/bb/milit...army_1-13.html