A job search on indeed.com (a job listing consolidator) within 25 miles of my area, Santa Monica, CA reveals

2,477 jobs for .NET

2,083 jobs for Java

1,284 jobs for python

685 jobs for Ruby

Here are # of questions with following tags on StackOverflow:

Java: 845,330

C#: 786,850

Python: 417,737

Ruby: 132,074

I can't speak for the rest of the world, but I would guess if you looked at 200 of the largest companies in Los Angeles, 90% of them have at least some .NET code running for something. It's pretty ubiquitous.

Games and business software are two huge industries which are almost entirely Windows. Everyone using the massively popular Unity engine is a C# developer.