https://www.zdf.de/nachrichten/panorama/corona-studie-impfdu...
https://www.zdf.de/nachrichten/panorama/corona-studie-impfdu...
Check out their weekly reports, the relevant tables are usually around page 21 or 22. In the most recent one, it's on page 24.
https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus...
The Ms. Wagenknecht said something similar with the numbers presented by you: From 3000 people on the ICU, 2/3 were unvaccinated. A pretty high number of Vaccinated.
Reference:
Not to mention that at this time the RKI was still counting reported hospitalizations into the "unvaccinated" category if there was no vaccination status known.
Currently that figure is at around 60% of all reported hospitalizations and can be checked by everyone, since the raw data is public.