HONG KONG (AFP) - As Hong Kong prepares to mark 20 years since it was handed back to China by colonial power Britain, we take a look at the numbers that make the city:

7.34 million

The number of people who live in Hong Kong. Parts of the city count as the most densely populated places on Earth with up to 50,000 people per square kilometre.

US$3,200

The median monthly household income. Hong Kong's poverty gap has reached a record high with many unable to afford rocketing property and rental prices.

US$700,000

The median price of a home, which is 18 times the annual median household income - the world's biggest gap. Values have been inflated by an influx of money from the mainland, while the government stands accused of colluding with developers. With 45.6 percent of residents already living in subsidised public housing, it is in increasingly short supply. 40 percent The proportion of land classified as protected country parks. There are fears these areas are now under threat as the government says it may need to develop rural zones for housing.

23

The number of consecutive years Hong Kong has ranked as the world's freest economy by the US think tank The Heritage Foundation. Low taxes, rule of law, and open markets places the city ahead of its next closest rival Singapore.

87

The average life expectancy for women and 81 years for men, the highest in the world. That is putting pressure on the city's pension system with many elderly residents working in gruelling jobs well past retirement age.

340,380

The number of foreign domestic helpers, the majority coming from the Philippines and Indonesia. Their welfare has been in the spotlight following several abuse cases by their employers, with whom they are required to live.

940,000

The number of mainland residents who have settled in Hong Kong since 1997, mostly as spouses and children of Hong Kongers.

297 million

Total number of passengers who travelled through Hong Kong last year on road, rail, sea and air. That is set to increase with massive infrastructure projects underway, including a third airport runway and a new road bridge linking directly with neighbouring Macau and the mainland city of Zhuhai.

US$13.8 billion

Amount wagered on horse races at the city's two race tracks last year, an obsession for many Hong Kongers. That compares with about US$12.8 billion spent by race-loving Britain, which has a population eight times the size.