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Greece is a developed country with an economy based on the service (82.8%) and industrial sectors (13.3%). The agricultural sector contributed 3.9% of national economic output in 2015. Important Greek industries include tourism and shipping. With 18 million international tourists in 2013, Greece was the 7th most visited country in the European Union and 16th in the world. The Greek Merchant Navy is the largest in the world, with Greek-owned vessels accounting for 15% of global deadweight tonnage as of 2013. The increased demand for international maritime transportation between Greece and Asia has resulted in unprecedented investment in the shipping industry.
How many international tourists were imprisoned in Greece in 2013?
A: unanswerable

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In 1358, the Sakya viceregal regime installed by the Mongols in Tibet was overthrown in a rebellion by the Phagmodru myriarch Tai Situ Changchub Gyaltsen (1302–1364). The Mongol Yuan court was forced to accept him as the new viceroy, and Changchub Gyaltsen and his successors, the Phagmodrupa Dynasty, gained de facto rule over Tibet.
What year was the Sakya viceregal regime eradicated? 
A: 1358

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Richmond is located at 37°32′N 77°28′W﻿ / ﻿37.533°N 77.467°W﻿ / 37.533; -77.467 (37.538, −77.462). According to the United States Census Bureau, the city has a total area of 62 square miles (160 km2), of which 60 square miles (160 km2) is land and 2.7 square miles (7.0 km2) of it (4.3%) is water. The city is located in the Piedmont region of Virginia, at the highest navigable point of the James River. The Piedmont region is characterized by relatively low, rolling hills, and lies between the low, sea level Tidewater region and the Blue Ridge Mountains. Significant bodies of water in the region include the James River, the Appomattox River, and the Chickahominy River.
How many square kilometers is Richmond?
A: 160

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Endemic species can be threatened with extinction through the process of genetic pollution, i.e. uncontrolled hybridization, introgression and genetic swamping. Genetic pollution leads to homogenization or replacement of local genomes as a result of either a numerical and/or fitness advantage of an introduced species. Hybridization and introgression are side-effects of introduction and invasion. These phenomena can be especially detrimental to rare species that come into contact with more abundant ones. The abundant species can interbreed with the rare species, swamping its gene pool. This problem is not always apparent from morphological (outward appearance) observations alone. Some degree of gene flow is normal adaptation, and not all gene and genotype constellations can be preserved. However, hybridization with or without introgression may, nevertheless, threaten a rare species' existence.
What causes genetic pollution?
A:
either a numerical and/or fitness advantage of an introduced species