(Bloomberg Gadfly) -- If you want to see why this weekend's cyberattack was so widespread, just look at the stubborn popularity of Microsoft Corp.'s Windows XP.
Almost 16 years since it was released, XP is the world's third most popular operating system -- even though Microsoft has long stopped releasing updates and the software has been superseded by more secure versions.
If you're still relying on old or outdated operating systems, you run an unnecessarily greater risk of falling victim to cybercrime. But XP is showing little sign of vanishing entirely: its rate of decline has slowed in recent years, as this chart shows.
That poor software hygiene may be because users are reluctant to change something that simply does the job, or risk an upgrade that could disrupt their business. But, with the threat of cyberattack increasing, it looks more and more like a flawed calculation.
To put it another way: would you keep your front door lock knowing that copies of your house keys are available to strangers?
This column does not necessarily reflect the opinion of Bloomberg LP and its owners.
Elaine He oversees Bloomberg Gadfly's data visualization work in Europe and also pursues her own columns combining business and markets coverage. Before joining Bloomberg, she was a graphics editor at the Wall Street Journal and the New York Times.