Gotta adjust for ticket price inflation. And in any case I doubt a downward trend from 7 -> 8 -> 9 is being celebrated internally at Disney as much as you're celebrating it.
I've done that already in other threads somewhere.
Although I doubt studios themselves would adjust for inflation. Wouldn't make sense, they'd be concerned about the current market.
They'd know that they'd never reach the same heights of episode 7, no studio ever could. Guaranteed that Avengers 5 won't make more than Endgame. They also knew that episode 9 would be an upward struggle after all the negativity that episode 8 got.
Episode 4, 5, 6 were on a downward spiral as well and I'm sure Fox didn't care as long as they made profit.
I'm sure Disney will be very happy with episode 9's numbers.
I'm sure they're happy to start fresh, refocus and move away from the Skywalker saga.
*FAKE EDIT*
Episode 4 - $503,000,000 = $2,100,000,000 today
Episode 5 - $400,000,000 = $1,200,000,000 today
Episode 6 - $374,000,000 = $965,000,000 today
Episode 1 - $924,000,000 = $1,426,000,000 today
Episode 2 - $640,000,000 = $915,000,000 today
Episode 3 - $849,000,000 = $1,118,000,000 today
Episode 7 - $2,068,000,000 = $2,224,000,000 today
Episode 8 - $1, 332,000,000 = $1,397,000,000 today
Rogue One - $1,056,000,000 = $1,131,000,000 today
Solo - $392,000,000 = $401,000,000 today
New movies are still doing pretty well apart from Solo.