I can't see how number of tickets sold is supposed to be more of an indication than inflation or anything else. There are a lot more movie theater seats now than there were back in the day of the first one. There are also more people on this planet by far. How many people were on the earth back at Star Wars IV? 1 billion? More people = more people to fill seats with. More seats = higher potential for people to watch the movie. Also, back then, I don't think they had midnight showings. So more showings also = more possible seats. So I really don't think there's really a way to capture everything unless you can tie in everything together. Number of possible views, number of seats, number theaters, number of people on the earth, etc. and even then that brings out the whole problem of oversaturation of the market because there were too many seats and the elasticity of demand for seats based on these different market conditions. Someone please shoot me before I keep going on...
In the end, who really cares? George Lucas is still making a killing on this. Right?