Relative click-through rates depending on your rank in Google

I came across this study, which describes the relative chance that a user will click on your link if they search in Google, depending on the rank it achieves in the search.

Rank 1 - 100%
Rank 2 - 100%
Rank 3 - 100%
Rank 4 - 85%
Rank 5 - 60%
Rank 6 - 50%
Rank 7 - 50%
Rank 8 - 30%
Rank 9 - 30%
Rank 10 - 20%

It's interesting that the first three positions rank equally (so there's no need to try too hard to get from position 3 to position 1), and that the percentages drop off quickly below that, when users have to start to scroll the screen to see your results.