Looking for something else, when I found
this in the UK's House of Commons Hansard for 5 Oct 09 (PDF attached), with the following caveats about the numbers shared:
.... The Ministry of Defence has recently completed a review of the data required to answer this question, and has revised the manner in which we classify and present data to ensure consistency.
The numbers of troops in contact events (regardless of the instigator) involving the International Security Assistance Force (ISAF) and insurgents in Helmand province as part of Task Force Helmand for each complete month from June 2006 to February 2009 for which verified data is available are shown below.
ISAF forces operating in Helmand come from a number of different nations, which often operate closely alongside each other and alongside Afghan Army and Police units. Without undertaking a detailed assessment of each engagement, it is not possible precisely to define in every case whether an attack was aimed at UK forces, at our ISAF partners, or against Afghan units. Data is therefore collected on the number of incidents involving ISAF forces in Helmand without attempting to identify the nationality of the forces actually being attacked. The environment in which forces are operating makes it extremely difficult precisely to distinguish between incidents initiated by insurgent forces and those initiated by ISAF.
This data is based on information derived from a number of sources and can only be an estimate, not least because of the difficulties in ensuring a consistent interpretation of the basis for collating statistics in a complex fast-moving multinational operational environment ....
Also interesting is the heading under which the question is classified:
"Afghanistan: Peacekeeping Operations"
