Since 2006[0]. I remember looking for a small user-friendly distro in 2008/9 that would fit my college-issued laptop's OEM emergency partition (5-ish GB). That partition was never used, as reimaging was the solution to almost every problem, yet they never bothered to delete it from the official images.
In the time and machines since, I've kept using Xubuntu.
In the time and machines since, I've kept using Xubuntu.
[0] https://en.wikipedia.org/wiki/Xubuntu