Which are the top 10 cities with the largest gambling populations?

The following list provides an estimation of the top 10 cities with the largest gambling populations:

1. Macau, China
2. Las Vegas, United States
3. Singapore, Singapore
4. Monte Carlo, Monaco
5. Atlantic City, United States
6. London, United Kingdom
7. Melbourne, Australia
8. Johannesburg, South Africa
9. Manila, Philippines
10. Niagara Falls, Canada