Frequency of new agency_ids in Complete Non-Realtime GTFS .zip

I am working on rules to manage overlapping agencies in the GTFS for real-time and the non-real-time complete GTFS file.

Do you know from experience how frequently new agency_ids without real-time are added to the non-realtime complete GTFS file?

Hi,

Based on our observation, a new agency ID of non-real time is usually added about once a year.