Census Spokeswoman Shelly Lowe tells us in an email that the jump "is due in part to an increase in households and a more rigorous tracking system."
Here's the breakdown of the 409 incidents so far:
* In 10 cases the Census worker was robbed, carjacked, or held against his or her will.
* In 13 cases shots were fired.
* There were 24 animal attacks or threats.
* There were 101 verbal assaults or threats.
* In 132 cases a weapon was pulled or use of a weapon was threatened.
* There were 88 physical assaults.
As the *Post* [reports](http://www.washingtonpost.com/wp-dyn/content/article/2010/06/19/AR2010061901896_pf.html), some of these incidents can be attributed to anti-government sentiment:
Sherri Chesney, 46, said she was cursed and spat at during follow-up visits in Houston. One day, she encountered a woman working in her garden. Chesney showed her census badge, she said, prompting the woman to launch into a tirade: "I don't need the blankety-blank government snooping in my business." Then she threw a metal patio table at Chesney, who escaped injury by ducking.