A History of Interest Rates
Zubin Al Genubi writes:
The all time usual rate is about 4% as I recall.
Jared Albert writes
https://www.bankofengland.co.uk/-/media/boe/files/working-paper/2020/eight-centuries-of-global-real-interest-rates-r-g-and-the-suprasecular-decline-1311-2018
The graphs are a ton of fun to flip through.