Microsoft's Windows 8 system has failed to match its predecessor's first-year sales numbers after the company confirmed 200 million license sales since launching the system 15 months ago, according to a report by Reuters.

Microsoft confirmed its Windows 7 reached 240 million license sales within its first year available.

The most recent Windows 8 sales figure was announced by Tami Reller, the company's head of marketing, at a Goldman Sachs technology conference on Feb. 13.

Slow sales for Windows 8, and its latest version, Windows 8.1, could be a product of a two-year decline in personal computer sales.

Most analyst expect sales of tablets to overtake PCs worldwide sometime in 2015.

Windows 8 was designed as a system that would be capable of working well on desktop PCs and devices like touchscreen tablets, but it ended up turning away loyal users.

The company's Surface tablet has also not won over many Apple iPad owners as well, according to Reuters.

The amount of people actually using Windows 8 is extremely low as well. Though a number of people and businesses technically have purchased Windows 8 licenses, many haven't installed the system on their PCs or other devices.

Tech statistics firm NetMarketShare reported only about 11 percent of PC users around the world are using Windows 8 or 8.1.

Approximately 48 percent are staying with Windows 7, and around 29 percent are still running Windows XP, which is almost 10-years-old.

Windows 7, which replaced Windows Vista, is Microsoft's most successful operating system to date, having sold over 450 million licenses, according to the company.

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