fonda approval due july-oct-says rbs, page-7

Re US fonda revenue, RBS say...

"...ACL receives a 50-60% share of profits from North American
sales from Dr Reddy?s, which equates to a ~35% revenue share."

Re ROW they say,

"...Dr Reddy?s pays ACL a royalty on sales at an agreed proportion. We assume this is equivalent to 20%."

Is there any basis for 20%, or have they just guessed a number? There's a big difference between 35% and 20%.