In its Basic Laws, Israel defines itself as a Jewish and democratic state. Israel is a representative democracy with a parliamentary system, proportional representation and universal suffrage. The prime minister serves as head of government and the Knesset serves as the legislature. Israel is a developed country and an OECD member, with the 35th-largest economy in the world by nominal gross domestic product as of 2015[update]. The country benefits from a highly skilled workforce and is among the most educated countries in the world with the one of the highest percentage of its citizens holding a tertiary education degree. The country has the highest standard of living in the Middle East and the fourth highest in Asia, and has one of the highest life expectancies in the world.