Your question made me curious myself. So I went back to my data. It turned out that I only started to collect initial margin by June 2021. Before that was I only collecting maintenance margin data (started in April 2017).I'm curious as to what your margin usage typically is.
A chart of the relative margin requirements are (margin as percentage of NLV), since the start of collecting initial margin:
The result surprises me a bit: this fluctuates much more than the impression I had of it.
Still catching up on that one....