An astute reader pointed out that some links on my site were 404'ing, so I ran a check for the first time in a couple of years. The results surprised me:

Year# Broken# Total%age
2007 80 50515.8%
2008361240015.0%
2009464305515.2%
2010314207415.1%
2011173108515.9%
2012243138417.6%
2013138 68220.2%
2014472111442.4%
2015250 96226.0%
2016100 65715.2%
2017 19 336 5.7%
2018 9 374 2.4%

The first surprise is the way the percentage of broken links stabilizes around 15% after a few years. The second is the massive jump in 2014; after a bit of inspection, that turns out to be caused by some posts I imported from the Software Carpentry site without fixing cross-links properly. The third surprise is the broken links from 2017 and 2018: I'm going to have to be more careful going forward.