Estonia is an industrial, agricultural country. It became an independent state at 1990, following the dissolution of the Soviet Union. During the Soviet occupation, their economy depended on the Russian industrialization politics, but after they followed the Scandinavian model to build up their economic system, based on the connection with Western-Europe, and investments from Finnland, Sweden, and Germany. Their most valuable mineral resources are the oil-shale and the peat. Similarly to the other Baltic states, Estonia has specialized in mechanical engineering too; their biggest industrial town is Tallin. Estonia's biggest exports are the agricultural goods, wood, textiles, and machines. The Tallin port is Estonia's largest and busiest, back in the days it was called Hanseatic City. Similarly to Latvia and Lithuania, the migration of workers is a problem for Estonia too, since their independence from the Soviet Union.