Rating the courtesy of the inhabitants of a country is subjective and can vary depending on personal experiences.  Here is a list, in no particular order, of ten countries that are often considered to have friendly and courteous people:

1. Japan: Courtesy and respect are fundamental in Japanese culture. The Japanese are generally kind, considerate, and committed to the well-being of others.
2. Canada: Canadians are famous for their friendliness and courtesy. They are known for apologizing even when they are not at fault and for their welcoming attitude towards foreigners.
3. New Zealand: New Zealanders are known for their friendliness and hospitality. They are usually warm, friendly and willing to help others.
4. Australia: Similar to New Zealanders, Australians are friendly and have a relaxed attitude towards life. They are known for their sense of humor and willingness to help visitors.
5. Norway: Norwegians are usually friendly, respectful and have an equal attitude towards others. They value courtesy and consideration for others.
6. Sweden: Swedes are known for being polite and friendly. They have a culture of equality and mutual respect that is reflected in their daily behavior.
7. Denmark: Danes are known for their courtesy and openness towards foreigners. They are usually friendly and willing to help others.
8. Singapore: The cultural diversity in Singapore has fostered an attitude of tolerance and courtesy among the inhabitants. Singaporeans are usually polite and respectful.
9. Switzerland: The Swiss are known for their punctuality, order and courtesy. They tend to be reserved but kind and respectful in their interactions.
10. Iceland: Icelanders are known for their kindness and hospitality towards visitors. They tend to be warm, welcoming, and willing to share their culture with others.

IN AMERICA

Costa Rica: Costa Ricans are known for their kindness and hospitality. They have a "Pura Vida" culture that reflects a positive attitude toward life and others.

1. Canada: As mentioned above, Canadians are famous for their friendliness and courtesy, making them a prominent presence both in North America and the world.
2. Uruguay: Uruguayans are known for their kindness and warmth towards visitors. They are usually courteous and willing to help others.
3. Chile: Chileans are usually friendly and hospitable. They have a welcoming attitude towards foreigners and are willing to share their culture.
4. Argentina: Despite Argentinians' reputation for their strong personalities, they are known for their warmth and kindness once you establish a relationship with them. They tend to be very courteous in their social interactions.
5. Mexico: Mexicans are known for their hospitality and generosity. They are usually friendly and willing to help visitors.
6. Peru: Peruvians are known for their kindness and cordiality. They usually welcome tourists with open arms and are willing to share their culture and traditions.

It is important to remember that these perceptions can vary depending on individual experiences and that courtesy is a quality found everywhere in the world, although it manifests itself in different ways.