Paper in rolls is almost exclusively what the photofinishing and photolab industry uses, so probably accounts for 98% of color paper. I don't know about black and white. But those kinds of systems have automated cutters and exposure systems, so don't use traditional easels much anymore. I have some Saunders easels with slots 8", 11" 18", 21", and 26" - all an inch over the paper sizes of 7", 10", 17" (rare nowadays), 20", and 24". For bigger paper still, I've my own vac easels.