From The Internet Archive’s “Orphan Works Reply Comments” (9 May 2005):
The Internet Archive stores over 500 terabytes of ephemeral web pages, book and moving images, adding an additional twenty-five terabytes each month. The short life span and immense quantity of these works prompts a solution that provides immediate and efficient preservation and access to orphaned ephemeral works. For instance, the average lifespan of a webpage is 100 days before it undergoes alteration or permanent deletion, and there are an average of fifteen links on a webpage.