The proportion of the country's population aged 15 and over attaining academic degrees is one of the lowest in the world, reaching 7.9% in 2011. An estimated 10.7% of the gross domestic product (GDP) is spent on education. Nauru has a universal health care system, and in 2012, an estimated 7.5% of its GDP was spent on healthcare. Nauru has the highest obesity ranking in the world; 97 per cent of men and 93 per cent of women are obese. In 2006, the average net monthly income was A$2,597 (A$ in 2014). The most significant sources of employment are phosphate mining, banking industries, and various coconut products. In 2011, the unemployment rate was 23%. The 2011 census enumerated 1,647 total households, averaging 6.0 persons per house. Average urbanisation rate in Nauru is 100%. With a population of ten thousand in 2011, Nauru ranks around 230th in the world by population. Its population density is 478 inhabitants per square kilometre (185 per square mile). The overall life expectancy in Nauru at birth is 59.7 years. The total fertility rate of 3.70 children per mother is one of the highest in the Oceania. The United Nations projects the population will stay around 10,000 in the 2020s, and the Nauru Bureau of Statistics estimates the population will increase to 20,000 in 2038. In Nauru's history, there have been six major demographics changes. The island was first inhabited by Micronesian people roughly 3,000 years ago. The first European to find the island was John Fearn in 1798. In 1888, the country was annexed by Germany. The next demographic change came when Japanese occupied the island during World War II in the 1940s. During this time, the Japanese deported several thousands of Nauruans to other islands. The next major demographic change was in the 1960s; the country gained independence, where the percentage of Nauruans started to increase. The last major demographics change was in 2006 when the Government of Nauru repatriated almost all of the remaining Tuvaluan and I-Kiribati workers, following large scale reduction from the Republic of Nauru Phosphate Corporation (RONPhos) and government workers. The census of 2006 stated 9,233 people were in Nauru: down 2.13% per year from the previous census of 2002. From 2002–11, there has been negative net migration, with an annual 109 net emigrants from 2006–11.