There’s the IMDB Starmeter, the Hollywood Reporter’s Top Actor’s Chart, and who knows how many analytic firms. It is worth noting that actors’ contracts are often backended with % bonuses based on gross profit. Cumberbatch could say that he and Tilda Swinton will be paid the same amount to co-star in Dr. Strange 2 but his deal could include % accelerations that hers does not. He could take this a step further and require his contracts and those of his costars to be made public in full.