With a population of 4,154,213 in 2016 Croatia ranks 126th in the world by population. Its population density is 75.8 inhabitants per square kilometre. The overall life expectancy in Croatia at birth is 78 years. The total fertility rate of 1.50 children per mother is one of the lowest in the world. Since 1991, Croatia's death rate has nearly continuously exceeded its birth rate. The Croatian Bureau of Statistics forecast that the population may even shrink to 3.1 million by 2051, depending on the actual birth rate and the level of net migration. The population of Croatia rose steadily from 2.1 million in 1857 until 1991, when it peaked at 4.7 million, with the exception of censuses taken in 1921 and 1948, i.e. following two world wars. The natural growth rate of the population is negative. Croatia started advancing from the first stage of the demographic transition in the late 18th and early 19th centuries (depending on where in Croatia is being discussed). Croatia is in the fourth or fifth stage of the demographic transition.