I think R was introduced in 2014 and discontinued in 2018 and overlapped with P for 1 year. There was no overlapping for R for 3 years so there could be more Rs out there compared to Gs. I also think we see a lot of 5231J. I was told I could get one this year (another client got one last year from the same AD) but I decided to pass as I prefer to wait for G or R versions.