What is the most popular language for machine learning?

When it comes to machine learning and data science, there are so many language options to choose from. Data scientist Jean-Francois Puget is looking at which one is best. What programming language should you learn to get a machine learning or data science job? I could provide my own answer to it and explain why, but I'd rather look at some data first. After all, this is what machine learners and data scientists should do: look at data, not opinions. So, let's look at some data.