Really, I would bet that 75% of them were in Saddam's military. That isn't bad.
Another perspective - look at a medium-sized city like Cleveland, Ohio. There are some 2.5 million people in the greater Cleveland area, including all of Cuyahoga County. 100,000 out of 2,500,000 isn't all that many - 4%. And Iraq has a lot more than 2,500,000 people - some 30 million according to 2008 estimates.