So far I have been able to get the PDFs from NFPA on their web site but 2020 doesn't seem to be up yet. You can get the interactive one online. If you are willing to live with the Draft from the ROPs they go back at least to the 50s. I found them when I was researching that down sized ground in RX. I downloaded 56, 68 and 71 in that quest. I also have the real ones since 96 in various formats mostly PDF.
