On reddit, brianlev, a Valve employee, explained what was actually happening:

“We did initiate a slow shift of the Skill Group boundaries recently, due to an increase in players and a substantial upward drift over time in the skill groups distribution. While this won’t impact the quality of your matches (you are matched based on an underlying rank value and not the visible Skill Group), many players will experience a change in their Skill Group as the distribution returns to a bell curve centered approximately at Gold Nova 4. We also shipped a recent update that will automatically monitor and maintain consistency of the players skill groups distribution. That should eliminate the need to make such disruptive boundary adjustments in the future.”

For the real stats enter sites {リンクが削除されました}https://csgosquad.com/ranks

Youtube
https://youtu.be/foe-_Zk8Wqk