Xbox Game Pass subscriber growth has fallen behind Microsoft's internal expectations.

According to a new financial filing, spotted by Axios, the number of Xbox Game Pass subscribers increased by 37 percent during the 12 months ended June 30, 2021, but the company had hoped to see growth of 48 percent.

It's unclear what those growth figures mean in terms of actual subscribers, although we do know Xbox Game Pass had topped 18 million subscribers at the start of the year.

Talking about that milestone back in January, Microsoft CEO Satya Nadella said consumers recognised the value of a "broader ecosystem," allowing the company to increase its console share.

The chief exec also touted Xbox Game Pass as a major revenue driver, and explained the entire Xbox Live ecosystem was attracting over 100 million active users each month.