Puerto Rico is not a country, but a territory of the US. Matter of fact, Puerto Ricans recently voted to become the 51st state of the USA. It still has to be granted by Congress though.
Don't know what your data source is but there are definitely countries missing. E.g. India or Switzerland are missing: https://en.wikipedia.org/wiki/List_of_countries_by_electricity_production_from_renewable_sources
http://www.curacaochronicle.com/region/puerto-rico-approves-us-statehood-bid/