Everyone knows Singapore is an expensive country that's transforming itself into a smart city. Here are five less-known facts about the island nation as it marks its 50th year of independence.

Costly cars

Car buyers in Singapore must bid for a limited number of permits -- called Certificates of Entitlement -- that are auctioned by the government. It's tool used to control pollution and congestion and can more than double the vehicle’s market value. Consequently, an average family sedan can cost almost as much as a home in the U.S.

Economic miracle

The country went from third world to first in two generations. Singapore took 22 years to double its GDP per capita, about half the time of other developed economies including Australia. Its GDP per capita was S$71,318 ($52,000) in 2014, among the highest in the world. The island also has among the highest proportions of millionaire households, according to Boston Consulting Group.

Living at home

The majority of housing in Singapore is built by the government. More than 80 percent of the resident population lives in such accommodation, which is typically cheaper than privately developed properties. Because of these dynamics and a rule that prohibits most single Singaporeans from buying a public housing apartment while single -- unless they are at least 35 years old -- an overwhelming majority of unmarried adults live with their parents. And are big fans of Airbnb.

Mandatory military service

Singapore is among a handful of developed nations with compulsory military service for its male residents and citizens. The National Service is for a period of about two years, and typically begins at age 18, unless there are exceptional circumstances -- like training for the Olympics, for example.

Highly paid ministers

Singapore's prime minister is among the world's highest paid heads of state. The government has justified his and other ministers' salaries on the grounds that it helps attract top talent that might otherwise be lost to the private sector, and that it discourages corruption. It cut ministers' salaries in 2012 after voter unhappiness over a widening income gap in the country. But they're still very comfortably off.