Bathroom query

Someone said to me, "Did you know there was a study that showed the vast majority of people close the bathroom door, even when they know there is no one else in the house? It's true!"

And I thought "people?"

What percentage of the world population has indoor plumbing?

I mean, I know there are still rural areas without it in the US, and we take our shit way too seriously.

So, how about South America? Africa? India? China? I mean, India and China combined make up 1/3 of the world's population, right? And, no offense, but you guys came late to the industrial revolution (or it fell upon you late, depending on perspective), so still have enormous markets for porcelain products, right?

Anyway, is it really the "majority" of people that close the bathroom door? Or just the majority in the self-obsessed industrialized nation where people have leisure time to do studies about people closing their bathroom doors?