Tourism in Singapore is a major industry and contributor to the Singaporean economy, attracting 17.4 million international tourists in 2017, more than 3 times of Singapore's total population. It is also environmentally friendly, and maintains natural and heritage conservation programs. Along with this, it also has one of the world's lowest crime rates. As English is the dominant one of its four official languages, it is generally easier for tourists to understand when speaking to the local population of the country, for example, when shopping. Transport in Singapore exhaustively covers most, if not all public venues in Singapore, which increases convenience for tourists. This includes the well-known Mass Rapid Transit (MRT) system.