Top Lifetime Adjusted Grosses
This chart can be found through Google, but there doesn't seem to be a link to it on the Box Office Mojo website anymore.
The FAQ describes the chart and also explains why it is important:
This is a helpful tool for converting box office earnings into a standard unit of measurement to better judge a movie's popularity and compare it to other movies released years or decades apart.
Overall, this method best compares "apples to apples" when examining the history of box office earnings.