Greece is a developed country with high standards of living[citation needed] and high Human Development Index. Its economy mainly comprises the service sector (85.0%) and industry (12.0%), while agriculture makes up 3.0% of the national economic output. Important Greek industries include tourism (with 14.9 million international tourists in 2009, it is ranked as the 7th most visited country in the European Union and 16th in the world by the United Nations World Tourism Organization) and merchant shipping (at 16.2% of the world's total capacity, the Greek merchant marine is the largest in the world), while the country is also a considerable agricultural producer (including fisheries) within the union.

The largest sector of Greece's economy is what?