The state achieved a very great population growth in the early 20th century, due to the golden period of rubber, and after installation of the Industrial Pole of Manaus, in the 1960s. The state still maintains population rates above the national average. In the 1950s the state had a population growth of 3.6% per year, while Brazil has maintained a growth of 3.2%. In the period between the years 1991 and 2000, Amazon grew by 2.7% per annum while the national average remained at 1.6%. For 2018, the estimate is 4,080,611 inhabitants.