Where are the scribbler files saved?


This concerns scribbler notes for PDF documents:
I’d like to backup the scribbler notes for my PDF to the cloud. In what folder can I find these notes.
Rationale: At the end of reading a PDF and making notes I export the annotated document into PDF. However, just to be on the safe side, I’d like to backup the notes while I am reading (which often takes days or even weeks).