Demographic features of the population of Yemen (سكان اليمن) include population density, ethnicity, education level, health of the populace, economic status, religious affiliations and other aspects of the population. The population of Yemen was about million according to estimates, with 46% of the population being under 15 years old and 2.7% above 65 years. In 1950, it was 4.3 million. By 2050, the population is estimated to increase to about 60 million. Yemenis are mainly of Arab ethnicity. When the former states of North and South Yemen were established, most resident minority groups departed. Yemen is still a largely tribal society. In the northern, mountainous parts of the country, there are some 400 Zaidi tribes. There are also hereditary caste groups in urban areas such as Al-Akhdam. According to the USCRI, Yemen hosted a population of refugees and asylum seekers numbering approximately 69 in 2017. Refugees and asylum seekers living in Yemen were predominantly from Iraq, Somalia, Ethiopia, and Syria. The ethnic makeup of Yemen consists predominantly of Arabs; but also includes minorities from the Horn of Africa, South Asia, and Europe. Yemen was formerly also home to a Jewish diaspora community. Arabic is the official language; English is also used in official and business circles. In the Mahra area (the extreme east), several non-Arabic languages (including Mehri) are spoken. When the former states of North and South Yemen were established, most resident minority groups departed. Religion in Yemen Religion in Yemen consists primarily of two principal Islamic religious groups: 55% of the Muslim population is Sunni and 44.5% is Shia. Others put the numbers of Shias at 40%. Sunnis primarily adhere to the Shafi'i school, and there are also significant followers of the Maliki and Hanbali schools. Shias are primarily Zaidi and also have significant minorities of Twelver and Ismaili Shias. Zaidis are generally found in the north and northwest and Shafi'is in the south and southeast. There is also a small minority of Christians and Jews.