iOS 9 seems to have gotten off to a strong start in its first few days of public availability. According to new data from Mixpanel, iOS 9 captured 21.79% of the overall iOS user base between its launch on September 16 and Friday, September 18. The previous version, iOS 8, still reportedly holds 71.66% of the iOS user base.

That iOS 9 has experienced a strong showing in its first couple of days isn't shocking. Unlike previous versions of the operating system, iOS 9 didn't leave a generation of hardware behind, allowing more people to make the upgrade. Additionally, the iOS 9 update size is smaller this year, meaning that devices with smaller storage space will have an easier time upgrading.

Apple's latest iOS share numbers, released just a couple of days before iOS 9's launch, showed that 87% of iOS devices were using iOS 8.

Source: Mixpanel