This graphic shows how many satellites are currently orbiting the Earth. They are broken down by nation and divided into functioning and non-functioning classes. As you might expect, the United States has the most functioning satellites (USA! USA!). But the world leader in space debris (Dead Satellite Division) is Russia. Those guys have so many dead hunks of metal flying through space it's kind of ridiculous.
Th United States has the most overall debris floating around the planet, but most of that is the result of our successful attempts to stop rogue asteroids and fight off alien invasions, so it's perfectly understandable.