I worked for the US Census Bureau in 2000... On average 3 census workers get killed each time they do a Census, and in 2010 there were somewhere around 400 individual incidents (of varying degrees of seriousness) of violence or threats of violence against Census workers.
I had one guy come to the door with a gun in his hand... I told him there were over a dozen of us working in his building that day, and if he shot me, they'd just send somebody else to ask him the same questions while he was lying face down with the cuffs on.