Serbia has been enduring a demographic crisis since the beginning of the 1990s, with a death rate that has continuously exceeded its birth rate. It is estimated that 300,000 people left Serbia during the 1990s, 20% of whom had a higher education. Serbia subsequently has one of the oldest populations in the world, with the average age of 42.9 years, and its population is shrinking at one of the fastest rates in the world. A fifth of all households consist of only one person, and just one-fourth of four and more persons. Average life expectancy in Serbia at birth is 76.1 years.