It look like a decline but these are relative numbers right? The whole industry exploded in size over this time period.

Does it matter if it's relative or absolute?

A relative decline in a segment where the overall total is growing might mean that the segment’s absolute number hasn’t gone down at all.

That’s like grasping at straws to avoid the truth. If the ratio of developers using ruby is dropping, the popularity of it is dropping.

Everything is ML focused now, and python is unfortunately the language most data scientists prefer.