The population of Denmark, as registered by Statistics Denmark, was 5.825 million in April 2020. Denmark has one of the oldest populations in the world, with the average age of 41.9 years, with 0.97 males per female. Despite a low birth rate, the population is growing at an average annual rate of 0.59% because of net immigration and increasing longevity. The World Happiness Report frequently ranks Denmark's population as the happiest in the world. This has been attributed to the country's highly regarded education and health care systems, and its low level of income inequality.