| Code | Name | Continent | Region | Population |
| ROM | Romania | Europe | Eastern Europe | 22,455,500 |
| RUS | Russian Federation | Europe | Eastern Europe | 146,934,000 |
| RWA | Rwanda | Africa | Eastern Africa | 7,733,000 |
| SAU | Saudi Arabia | Asia | Middle East | 21,607,000 |
| SDN | Sudan | Africa | Northern Africa | 29,490,000 |
| SEN | Senegal | Africa | Western Africa | 9,481,000 |
| SGP | Singapore | Asia | Southeast Asia | 3,567,000 |
| SGS | South Georgia and the South Sandwich Islands | Antarctica | Antarctica | 0 |
| SHN | Saint Helena | Africa | Western Africa | 6,000 |
| SJM | Svalbard and Jan Mayen | Europe | Nordic Countries | 3,200 |
| SLB | Solomon Islands | Oceania | Melanesia | 444,000 |
| SLE | Sierra Leone | Africa | Western Africa | 4,854,000 |
| SLV | El Salvador | North America | Central America | 6,276,000 |
| SMR | San Marino | Europe | Southern Europe | 27,000 |
| SOM | Somalia | Africa | Eastern Africa | 10,097,000 |
| SPM | Saint Pierre and Miquelon | North America | North America | 7,000 |
| SSD | South Sudan | Africa | Northern Africa | 12,340,000 |
| STP | Sao Tome and Principe | Africa | Central Africa | 147,000 |
| SUR | Suriname | South America | South America | 417,000 |
| SVK | Slovakia | Europe | Eastern Europe | 5,398,700 |