Tour de France
I look at some data of the Tour de France for the years 2005 - 2012 (2009 not included) to see if there are some differences in patterns. Lately, much is said about how cycling has become a cleaner sport and, often, commenters will point out that the times to reach mountain summits has dropped.
This project provides a more extensive overview over all the different data. For every year, I collect the speed for every rider overall, in the mountains and in time trials. Plotting this over time (e.g. using a boxplot) can provide some more insight in how credible the claims for a cleaner sport are.
2005 was the last year Lance Armstrong won the Tour de France while using doping. Numerous yellow jersey riders in 2006 and 2007 also officially stated using doping (Floyd Landis, Michael Rasmussen among others).
The data presented do not necessarily serve as proof for either position, but as some kind of indication of how likely it is cyclists still use doping (for the Tour de France).
Many thanks to Martin Theus, since I have used the data he put online!