Helsinki continued to develop steadily despite the chaotic first half of the 20th century. The rapid urbanization of Helsinki in the 1970s was later than in other parts of Europe. Later, in the 1990s, the population of the metropolitan area tripled, making the Helsinki metropolitan area one of the fastest growing urban centers in the European Union at the time. . Helsinki's relatively small population density and its unique structure are attributed to its slower urbanization process. Today Helsinki is the second fastest growing capital city in Europe, second only to Brussels.