 Each of the next six decades saw a 15.0% rise in population, reaching 3.41 million in 1960.Growth then slowed, rising 11.0% to 3.8 million in 1970, and an average of 9.0% over the next three decades to 4.91 million in the 2000 census.The rate of population change, and age and gender distributions, approximate the national average.