Friday’s New York Times has a nice graph that describes movies in terms of their box office receipts and longevity. The height is a measure of weekly box office receipts, and the width is in time.
So the movie which people continued to watch even after the first few weeks, will exist on the chart for a longer width. For instance, Harry Potter and the Order of the Phoenix goes from June/July ’07, all the way to December ’07. On the other hand, Resident Evil: Extinction only goes from September to mid-October of ’07.
And movies which occupy a greater area, earned more. For example, National Treasure: Book of Secrets (which is still in theaters, but with rapidly diminishing revenues) has made between $100-250 million so far. Though, I Am Legend has made between 250-862 million.
Click on the picture of the chart, to take you to the original chart.