So I found a cool tool on the internet, and made this nifty visualisation of the concentration of navaids per country (as of the navaid data at [OurAirports] (www.ourairports.com/data), I doubt this is 100% complete but it has a pretty good list. VORs and NDBs (and their various variations) are counted)
The US is of course the highest, with over 2000. There are 2 main factors coming down to a high concentration of Navarids- country size and wealth. The UK with 188 navaids has more than any country in Africa, most of which have a much larger area.
Here is a link for those who want more detail: