<Table> Economy of Singapore <Tr> <Td_colspan="2"> Skyline of Singapore's CBD </Td> </Tr> <Tr> <Th> Currency </Th> <Td> Singapore dollar (SGD / S $) </Td> </Tr> <Tr> <Th> Fiscal year </Th> <Td> 1 April--31 March </Td> </Tr> <Tr> <Th> Trade organisations </Th> <Td> WTO, APEC, IOR - ARC, ASEAN </Td> </Tr> <Tr> <Th_colspan="2"> Statistics </Th> </Tr> <Tr> <Th> GDP </Th> <Td> US $349.7 billion (nominal; 2018 est .) US $554.9 billion (PPP; 2018 est .) </Td> </Tr> <Tr> <Th> GDP rank </Th> <Td> <Ul> <Li> 37th (nominal) </Li> <Li> 39th (PPP) </Li> </Ul> </Td> </Tr> <Tr> <Th> GDP growth </Th> <Td> 3.6% (2017) </Td> </Tr> <Tr> <Th> GDP per capita </Th> <Td> US $61,766 (nominal; 2018 est .) US $98,014 (PPP; 2018 est .) </Td> </Tr> <Tr> <Th> GDP per capita rank </Th> <Td> <Ul> <Li> 9th (nominal) </Li> <Li> 3rd (PPP) </Li> </Ul> </Td> </Tr> <Tr> <Th> GDP by sector </Th> <Td> Agriculture: 0% Industry: 26.6% Services: 73.4% (2016 est .) </Td> </Tr> <Tr> <Th> Inflation (CPI) </Th> <Td> 0.4% (August 2017) </Td> </Tr> <Tr> <Th> Population below poverty line </Th> <Td> N / A </Td> </Tr> <Tr> <Th> Gini coefficient </Th> <Td> 46.4 (2014) </Td> </Tr> <Tr> <Th> Labour force </Th> <Td> 3.661 million (2016 est .) </Td> </Tr> <Tr> <Th> Labour force by occupation </Th> <Td> Agriculture: 0.96% Industry: 15.5% Services: 83.5% (2016 est) </Td> </Tr> <Tr> <Th> Unemployment </Th> <Td> 2.1% (December 2017) </Td> </Tr> <Tr> <Th> Main industries </Th> <Td> <Ul> <Li> Electronics </Li> <Li> chemicals </Li> <Li> financial services </Li> <Li> oil drilling equipment </Li> <Li> petroleum refining </Li> <Li> rubber </Li> <Li> food and beverages </Li> <Li> ship repair </Li> <Li> offshore construction </Li> <Li> life sciences </Li> <Li> entrepot trade </Li> </Ul> </Td> </Tr> <Tr> <Th> Ease - of - doing - business rank </Th> <Td> 2nd (2018) </Td> </Tr> <Tr> <Th_colspan="2"> External </Th> </Tr> <Tr> <Th> Exports </Th> <Td> US $329.7 billion (2016) </Td> </Tr> <Tr> <Th> Export goods </Th> <Td> <Ul> <Li> Machinery and Equipment Electronics and Telecommunications Pharmaceuticals and Other Chemicals Refined Petroleum Products </Li> </Ul> </Td> </Tr> <Tr> <Th> Main export partners </Th> <Td> <Ul> <Li> China 13% </Li> <Li> Hong Kong 12.6% </Li> <Li> Malaysia 10.6% </Li> <Li> European Union 9% </Li> <Li> Indonesia 7.8% </Li> <Li> Other 47% </Li> </Ul> </Td> </Tr> <Tr> <Th> Imports </Th> <Td> US $282.9 billion (2016) </Td> </Tr> <Tr> <Th> Import goods </Th> <Td> <Ul> <Li> Machinery and Equipment Mineral Fuels Chemicals Foodstuffs Consumer Goods </Li> </Ul> </Td> </Tr> <Tr> <Th> Main import partners </Th> <Td> <Ul> <Li> China 14.3% </Li> <Li> European Union 13.6% </Li> <Li> Malaysia 11.4% </Li> <Li> United States 10.9% </Li> <Li> Taiwan 8.2% </Li> <Li> Other 41.7% </Li> </Ul> </Td> </Tr> <Tr> <Th> FDI stock </Th> <Td> Inward: US $1.096 trillion Outward: US $682.4 billion (2016) </Td> </Tr> <Tr> <Th> Current account </Th> <Td> US $61.172 billion (2015 est .) </Td> </Tr> <Tr> <Th> Gross external debt </Th> <Td> US $1.32 trillion (30 June 2017) </Td> </Tr> <Tr> <Th> Net international investment position </Th> <Td> S $738.811 billion (Q1 2015) </Td> </Tr> <Tr> <Th_colspan="2"> Public finances </Th> </Tr> <Tr> <Th> Public debt </Th> <Td> 110.5% of GDP (2016 est .) </Td> </Tr> <Tr> <Th> Revenues </Th> <Td> S $69.45 billion (2017 est .) </Td> </Tr> <Tr> <Th> Expenses </Th> <Td> S $75.07 billion (2017 est .) </Td> </Tr> <Tr> <Th> Economic aid </Th> <Td> None </Td> </Tr> <Tr> <Th> Credit rating </Th> <Td> <Ul> <Li> Standard & Poor's: AAA (Domestic) AAA (Foreign) AAA (T&C Assessment) Outlook: Stable </Li> <Li> Moody's: Aaa Outlook: Stable </Li> <Li> Fitch: AAA Outlook: Stable </Li> </Ul> </Td> </Tr> <Tr> <Th> Foreign reserves </Th> <Td> US $279 billion (October 2017) </Td> </Tr> <Tr> <Td_colspan="2"> Main data source: CIA World Fact Book All values, unless otherwise stated, are in US dollars . </Td> </Tr> </Table> <Tr> <Td_colspan="2"> Skyline of Singapore's CBD </Td> </Tr>

What is the main source of income in singapore
find me the text answering this question