As part of the Soviet Union, the Armenian SSR transformed from a largely agricultural hinterland to an important industrial production center, while its population almost quadrupled from around 880,000 in 1926 to 3.3 million in 1989 due to natural growth and large-scale influx of Armenian genocide survivors and their descendants. On 23 August 1990 the Declaration of Independence of Armenia was adopted. On 21 September 1991, the independence of the Republic of Armenia was confirmed in a referendum. It was recognized on 26 December 1991 when the Soviet Union ceased to exist. After the dissolution of the Soviet Union, the state of the post-Soviet Republic of Armenia existed until the adoption of the new constitution in 1995.