It's one of the most stable ones there and has been for quite a long time. I've driven in an around in a few times but not since about 2003 or so. It's probably changed quite a bit I think, especially considering the photo of the hotel in Windhoek is something I've never seen when I was last there.
I'm surprised that Tunisia is behind Morocco. Alas I've never been to subsaharan Africa - someday, I hope. I thought ZA would be the richest country. I'm also surprised that Senegal is richer than Nigeria - I guess there must be a huge income divide in that country.