Here are some interesting numbers from an article about space debris:
With some 900 active satellites in orbit (nearly half of them American) there is a need to provide better tracking of dangerous space junk. About 75 percent of all satellites are non-military (most of them commercial, the rest government non-military birds).
So... (0.25 military) * (0.5 American) == (0.125 American military)
That seems like a very high proportion.