Gävle is a Swedish city in east central Sweden with 81,000 inhabitants, and the seat of Gävle Municipality (pop. 92,000). It is one of the oldest cities in the historical Norrland (Sweden's Northern lands), as it received its charter in 1446 by Christopher of Bavaria. Gävle is situated by the Baltic Sea near the mouth of the river Dalälven. At 60 degrees north and 17 degrees east, Gävle has the same latitude as Helsinki and the same longitude as Vienna and Cape Town. Gävle has a similar climate to the rest of central Sweden with an average temperature of -5 C in January and +17 C in July. Yearly rainfall is around 600mm. Trade from the port of Gävle increased markedly during the 1400s when copper and iron began to be exported from the port. In order to ensure that all trade was via Stockholm, sailing to foreign ports from Gävle and a few other ports was forbidden. Today there are few shipping companies or shipyards left, but an important port remains. It has over 1000 ships calling per annum and is among the top ten common ports in Sweden.