I don't think the box office is a good success indicator. When you see the top 10 of the list, most of them are recent movies released in 3D, because the price of a 3D movie ticket (or IMAX) is mostoften more expansive thant an other (it is the case in France). Moreover because of the inflation, one billion in 60's is not comparable with a billion today, as said RMc.
The better way to know what is a successful movie is the number a tickets sold.
Excellent point, I'd forgotten the IMAX premium for SF. If we could get hold of accurate ticket sales figures, that'd be the best comparison.
I guess the most accurate way would be to compare the average number of tickets sold per cinema/theater? That might take into account greater accessibility to the silver screen?
In the Skyfall Box Office thread, I'm pretty sure these issues have been addressed. If I remember correctly, I believe Skyfall sold more tickets than Thunderball, making it without doubt the most successful Bond of all time.
Very happy the rumor mill has started up again.