/* Available in MySQL, SQL Server, PostgreSQL */
SELECT
CountryCode,
Name,
(CUME_DIST() over p_code) * 100 AS percent
FROM city
WHERE
CountryCode IN ('AFG', 'CHE')
WINDOW p_code AS (PARTITION BY CountryCode ORDER BY Population)
| CountryCode | Name | percent |
| AFG | Mazar-e-Sharif | 25.0 |
| AFG | Herat | 50.0 |
| AFG | Qandahar | 75.0 |
| AFG | Kabul | 100.0 |
| CHE | Lausanne | 20.0 |
| CHE | Bern | 40.0 |
| CHE | Basel | 60.0 |
| CHE | Geneve | 80.0 |
| CHE | Zürich | 100.0 |