I think there is a possibility that this year's figures will be significantly higher.
The resignation agency service was widely reported in Japanese media in the first half of this year, which made its existence known to the public. This trend can also be confirmed on Google Trends[1].
In fact, the representative of 退職代行モームリ (Taishoku-daikō Mōmuri), the largest resignation agency company, stated in an interview that the number of users during this year's onboarding season was ten times that of last year[2].
> "上半期（2024年1月～6月）に退職代行サービスを利用して退職した人がいた企業は23.2％だった。また、過去の退職代行利用者の実績を年度別に聞くと、2021年は16.3％、2022年は19.5％、2023年は19.9％"
These seem like full-year numbers, but they're much lower than what I'd expect if 23.2% is the half-year number — implying a huge jump in 2024?