Archive Value Of News Pictures

I have a theory that a very high percentage of the uses of editorial or news pictures occur in the first month or two after they are shot. Newpapers, magazines and websites use the images when they are fresh and then move on to the next news happening. Of course, certain events will have historical value and key images from these events may be used over and over in future years – Iwo Jima flag raising, World Trade Center, Hindenburg crash, etc.– but it seems to me that such situations represent a very small percentage of overall use.