This seems to assume a fixed number of programmers, all of whom program during the week and at the weekend. My guess would be that it's much more likely to be

This seems to assume a fixed number of programmers, all of whom program during the week and at the weekend. My guess would be that it's much more likely to be two largely disjoint sets: Professional programmers at work during the week, and amateur programmers who have other day jobs (e.g. school or non-programming jobs) who are more likely to be programming during the weekends. If we assume that this is the case, then the data simply suggests that professional programmers are more likely to use C# and Java, whereas hobbyist/amateur programmers are more likely to use Python or Ruby. This is just a hypothesis, but it is equally well supported by the data as the article's hypothesis: programmers choose to use languages like Python and Ruby for their personal projects, despite their weaknesses, because these languages are more fun to program in Which assumes that all professional programmers are also hobbyist programmers in the weekends, and that the numbers of amateur programmers are not significant enough to make an impact on search statistics.