Sweden had played a passive role in international trade during the 16th century; German merchants and ships managed the export of Swedish primary products such as osmond iron, raw copper, and butter. This export was largely regarded as a means of securing the import of items not available in Sweden, such as salt, wine, and luxury goods demanded at the court. With the introduction of a mercantile doctrine around 1620, trade became a keystone to governmental income and the Swedish economy subsequently focused on export, not of raw materials, but of refined products. Over the entire period (c. 1590–1685), Stockholm's share of the national economy remained stable at around two-thirds, but during the first half of the 17th century, export grew fourfold and import fivefold. Most goods were delivered to the Netherlands in the mid-17th century and to the UK in the early 18th century.