Web Stability

We offer a database of the online resources we encounter in our activities. There are approximately 550 links in our collection. Approximately twice a year I go through the entire collection to search for dead links. I have taken to keeping track of he number of links that do not function and I am unable to locate with a Google search. This time the number was 12. Obviously, the number of links is partly a function of the type of resources I collect. However, this seems a small % and one way to quantify the stability of web resources.