You're wondering what that star is for, right? Inflation, basically.
As long as you don't adjust for inflation, Andy Muscietti's adaptation of Stephen King's It is the highest-grossing horror film of all time with a whopping $478,038,881 made so far from both US and international box offices. William Friedkin's 1973 horror The Exorcist totalled $441,306,145 during its run. However, when we adjust for inflation to 2017 figures, The Exorcist would make - wait for it - $983,226,600.
So yeah, It may have surpassed The Exorcist in terms of figures, but when you adjust that against the amount of tickets sold, it looks The Exorcist is still on top. Still, they're both excellent horror films so they're both winners in our mind.