ABC News' Kristina Wong reports: New statistics on U.S. contractor deaths in Afghanistan were released earlier this week. They show that U.S. contractor deaths are soaring, from 189 last June 30th since the war began in 2001, to 521 this June 30th – an increase of 175% in just one year. These numbers include armed private security contractors, as well as those working on development programs, who are American, Afghan and third-country nationals working under a U.S. contract. Statistics can be found here. However, since there could be as many as 120,000 to 125,000 contractors in Afghanistan, 521 deaths comprise only a small percentage of total contractors in Afghanistan, roughly 0.4%. But according to the Department of Labor website, these numbers do not constitute the complete or official casualty statistics of civilian contractor deaths — just the ones insurance claims have been filed for, so the percentage could be higher. Also, they do not count contractors hired directly by the U.S. government (not just under a U.S. contract), and it is unclear whether they include Afghans who participate in cash-for-work programs. To date, there is no reliable way of tracking how many U.S. contractors there are in Afghanistan, according to experts at the Commission for Wartime Contracting, and SIGAR. The Department of Defense is the only agency that regularly tracks and publishes its count each FY quarter. By the end of March 2010, it had 112,092 contractors in Afghanistan. Going by the DOD’s contractor statistics alone, there was an increase from 73,968 last June to 112,092 this March – a 52% increase, accompanying the rise in U.S. and coalition troops in the past year. Thus, while the number of DOD contractors rose about 52% in the last year, the number of contractor deaths during that time rose 175%. Meanwhile, NATO military casualties increased by 57% from last year, and U.S. military casualties rose by 60% from last year, according to http://icasualties.org/ statistics. "In reality it's a contractor surge," Allison Stanger, author of "One Nation Under Contract”, said in a phone interview with ABC News, about the dramatic rise of contractors in Afghanistan. "It's the Pentagon and the State Department trying to do what they were asked to do without the resources." A U.S. official told ABC News last week that the Taliban targeting U.S. contractors " is very clear tactic of the Taliban." The official said in Kandahar city, where Operation Hamkari is taking place, vulnerable contracting companies are being given the option to locate their headquarters on a forward operating base, co-located with the International Security Assistance Force or the U.S. military.