I’ve just updated the Competition Use section of The Popularity of Data Science Software. Here’s just that section for your convenience.
Kaggle.com is a web site that sponsors data science contests. People post problems there along the amount of money they are willing pay the person or team who solves their problem the best. Both money and the competitors’ reputations are on the line, so there’s strong motivation to use the best possible tools. Figure 9 compares the usage of the top two tools chosen by the data scientists working on the problems. From April 2015 through July 2016, we see the usage of both R and Python growing at a similar rate. At the most recent time point Python has pulled ahead slightly. Much more detail is available here.