binary firmware

A little while ago I saw an interesting tweet from Stephen O'Grady at RedMonk on the state of open source licensing, including this graph. This graph shows how license usage has changed from 2010 to 2017. In reading it, it is clear that usage of the GPL 2.0 license, one of the purest copyleft licenses around, has more than halved in usage. According to the chart it would appear that the popularity of open source licensing has subsequently shifted to the MIT and Apache licenses. There has also been a small increase in GPL 3.0 usage. So, what does all this mean?