February 2011. Foreign citizens make.5 of the population, while the total immigrant population makes.5. "Helsingin Aallot" blog (in Finnish). 47 48 Helsinki has experienced strong growth since the 1810s, when it replaced Turku as the capital of the Grand Duchy of Finland, which later became the sovereign Republic of Finland. 51 Some residents began to move to the neighbouring cities of Espoo and Vantaa, resulting in increased population growth in both municipalities.