Maciej Ceglowski is the founder of the wonderful, superb, and totally useful Pinboard social (if you want to be) bookmarking service that expressed a lot of love towards the library world last Christmas.
Along with the pretty graph [included in the post], I’ve published the detailed results by year here. Links appear to die at a steady rate (they don’t have a half life), and you can expect to lose about a quarter of them every seven years.
The post also contains Ceglowski’s methodology
We use Pinboard around here 24×7. A one time registration fee is $9.34/U.S and for $25/year you can use their archiving service that automatically (unless you turn it off) attaches a great looking cached copy of each page (or PDF) to the bookmark entry. Cached copies are created at the time you bookmark the page. Also some very useful auto-bookmarking features are described at the bottom of this section of the site tour.
One final note. While Pinboard is most often referred to as bookmarking site, here’s what Ceglowski thinks of his service:
Link rot in my own bookmarks is what first inspired me to create Pinboard, a personal archive* disguised as a social bookmarking site.
* Our Emphasis
See Also: “Link Rot” and Legal Resources on the Web: A 2011 Analysis by the Chesapeake Digital Preservation Group”
This is the fourth annual report. It was published in April.