The Stockholm region is home to around 22% of Sweden's total population, and accounts for about 29% of its gross domestic product. The geographical notion of "Stockholm" has changed over time. By the turn of the 19th century, Stockholm largely consisted of the area today known as City Centre, roughly  or one-fifth of the current municipal area. In the ensuing decades several other areas were incorporated (such as Brännkyrka Municipality in 1913, at which time it had 25,000 inhabitants, and Spånga in 1949). The municipal border was established in 1971; with the exception of Hansta, in 1982 purchased by Stockholm Municipality from Sollentuna Municipality and today a nature reserve.