Some fascinating info here - https://docs.google.com/spreadsheet/ccc?key=0Au3uvK2N0fk_dGlmMnQyVnI3aHdXUFBjMmJsbjRsYXc#gid=0 and here http://www.wired.com/dangerroom/2011/09/dangerroom_911toll_0909/all/1