 Fertility rates have also decreased from 5.7 children per woman in 1976 to 2.2 in 2006.The average annual population growth rate of Mexico City was the first in the country at 0.2%.The state with the lowest population growth rate over the same period was Michoacán (-0.1%), whereas the states with the highest population growth rates were Quintana Roo (4.7%) and Baja California Sur (3.4%), both of which are two of the least populous states and the last to be admitted to the Union in the 1970s.