File photo: Microsoft chairman Bill Gates speaks during the product launch of the Windows XP operating system in 2001.

More than 16 percent of all PC users who agreed to provide data to the distributed global Kaspersky Security Network were still working on computers running Windows XP in June 2014.

This fact carries potential implications for information security. This number was part of the findings from the “Windows usage and vulnerabilities research” carried out by Kaspersky Lab experts in 2014.

Users whose computers run under a dated operating system or have out-of-date versions of installed software risk coming under attack from malware that exploits vulnerabilities.

The study assessed the proportion of Windows XP users among all users of Kaspersky Lab's Windows-based products in each country.

Vietnam was the leader, with 38.79 percent of users still preferring to work under Windows XP. Next came China with 27.35 percent, India with 26.88 percent, and Algeria with nearly a quarter (24.25 percent) of users still remaining loyal to the legendary operating system.

Roughly one in five computers protected by a Kaspersky Lab product still runs under Windows XP in Italy (20.31 percent) and Spain (19.26 percent). A smaller proportion of users – 4.52 percent continues to use Windows XP in the USA.

Although technical support for Windows XP users was only discontinued in April 2014, the sales of this operating system finished back in 2010.

This, however, did not have much effect on its popularity: according to Kaspersky Lab data in June 2011, a year after the end of sales, 48.86 percent of users were still using Windows XP.

After another year, in June 2012, there were 35.64 percent, and in June 2013, 25.42 percent of Windows XP users. Stated differently, the popularity of Windows XP decreased roughly by 10 percentage points each year.

Interestingly, that decline was not greatly affected by external events which could potentially have accelerated it, such as the release of Windows 8.1 in October 2013 or the discontinuation of the extended Windows XP support: in November 2013, there were 21.42 percent XP users; by June 2014 the number fell to 16.37 percent, which makes a 5.05 percentage points' decline, or roughly a half of the total annual decline in XP’s popularity.

In contrast, Windows 8.1, the newest Windows operating system to date, had a 7.22 percent market share in June 2014.

This result is 1 percentage point better than its precursor Windows 8 had at the equivalent stage: from late October 2012 to June 2013, Windows 8 was installed on the computers of 6.22 percent of Kaspersky Lab product users.

The improved take-up rate for Windows 8.1 may be partly related to the fact that Windows 8 was the first Microsoft operating system which supports upgrades to new versions with an embedded upgrade client via the official Windows app store.

Besides, Windows 8 users had a free option to upgrade to Windows 8.1, which also played a role in how fast the new version was adopted.