That is a valid point, So if we are to comapre only domestic collocations (North American)

Superman Returns(2006)---------- $200,081,192

Thor(2011)--------------------------$181,030,624

If we take into account higher ticket prices due to the 3D factor and inflation since 2006 to 2011, the number of people who actually saw Thor in theaters will be significantly less.

Edit: Some poster here on SHH boards has said that when comparing the average price of a 2D movie ticket with a 3D movie Ticket costs 15 % more in US, so he suggested dividing the amount earned by a 3D movie by 1.15 so that it can be compared with a 2D movie ticket price.

If we do that for Thor then modified collections Thor's would be $157.417 mil which is less than SR's domestic collection of $ 200.081 mil.