Identify this country: It is a small sovereign city-state located in South Western Europe on the northern central coast of the Mediterranean Sea. It is famous as a tax haven, and wealthy foreigners make up the majority of the population, around 84%.

Monaco is a small sovereign city-state on the French Riviera in South Western Europe, bordering the Mediterranean Sea. It is indeed famous as a tax haven and has a very high proportion of wealthy foreign residents (around 84% of the population). Montenegro, Slovenia, and Kazakhstan are all much larger countries and don't match the description.