Very few. I can't actually name any, but most instruments have their basis in ancient civilisations e.g. Egyptian, Arabic in particular etc. The only truly modern instruments would appear to be electronic ones.
In this case, non-synthesiser electronic instruments seem to originate mostly from the French e.g. the ondes martenot, the theremin etc. Modern synthesisers seem to be of US origin.
The one glimmer of hope is if you regard laptops as instruments- computers are (unofficially) a British invention.