A decade after the Sept. 11, 2001, attacks on the World Trade Center and the Pentagon, federal and state governments are spending about $75 billion a year on domestic security, setting up sophisticated radio networks, upgrading emergency medical response equipment, installing surveillance cameras and bombproof walls, and outfitting airport screeners to detect an ever-evolving list of mobile explosives. But how effective has that 10-year spending spree been? The number of people worldwide who are killed by Muslim-type terrorists, Al Qaeda wannabes, is maybe a few hundred outside of war zones. It's basically the same number of people who die drowning in the bathtub each year," said John Mueller, an Ohio State University professor who has written extensively about the balance between threat and expenditures in fighting terrorism. "So if your chance of being killed by a terrorist in the United States is 1 in 3.5 million, the question is, how much do you want to spend to get that down to 1 in 4.5 million?" he said. The vast network of Homeland Security spyware, concrete barricades and high-tech identity screening is here to stay. The Department of Homeland Security, a collection of agencies ranging from border control to airport security sewn quickly together after Sept. 11, is the third-largest Cabinet department and - with almost no lawmaker willing to render the U.S. less prepared for a terrorist attack - one of those least to fall victim to budget cuts.