This is not as bad as it sounds. You need to consider the absolute numbers than the relative percentages for languages like C++.

Programming is more accessible than ever before, more jobs require some element of programming than ever before, and more things are getting created using code. This means that people who have never written code before are writing code as a job of work, and are writing it in simpler-to-learn languages.

Newer, simpler programming jobs are acquiring programmers in other languages, not necessarily that C++'s complexity is driving people away from it into the arms of other languages or that C++ is not acquiring newer programmers at the same rates (on existing base) as before.