"This statute requires the State Department to include in its annual report on terrorism 'to the extent practicable, complete statistical information on the number of individuals, including United States citizens and dual nationals, killed, injured, or kidnapped by each terrorist group during the preceding calendar year.' NCTC [National Counterterrorism Center] keeps statistics on the annual number of incidents of 'terrorism,' but its ability to identify the specific group responsible for each incident resulting in death, injury or kidnapping is significantly limited by the availability of reliable open source information, particularly when attacks involve few casualties or occur in remote regions of the world. Moreover, specific details regarding victims, perpetrators, damage or other elements of the incident are frequently not fully addressed in open source reporting. [...] Therefore, the statistical material in this report reflects the most comprehensive body of information available to NCTC for compiling data to satisfy the above-referenced statistical requirements and details incidents of 'terrorism' that occurred in 2009 as reported in open source information."
National Counterterrorism Center: http://www.nctc.gov/