Additionally, the driver for the huge volume increase was partly Listerine going down market from an expensive medicine to a mass market product. $20 in 1881 is apparently equivalent to $580 now. J&J probably only get around $200 revenue for each gross of Listerine sold now (a guess based on retail prices and markups), suggesting that despite inflation the royalty is still a respectable 10% but implying the 1881 price must have been much higher, in real terms, than Listerine costs now.