As far as we know, the yearly volume is commonly quite low.
The current format allows sending up to ten thousand files between each submitter and recipient, which was increased from an original one hundred, but probably no submitter will send so many files.
CWR files are commonly sent by publishers each trimester, but can amount to up to four per year.
Societies on the other hand may not send a single CWR file in a year, but may reply to any and all received files with an acknowledgement file.
A single group may contain up to ten million transactions, and there can be a hundred thousand groups. But again, this limit seems hard to reach.
A big file will contain around a hundred thousand agreements, which will mean a few hundred thousand lines. While a smaller one will just have less than ten thousand lines.