Net foreign assets is foreign assets minus foreign liabilities. Values are measured at market exchange rates in constant 2018 US dollars, using a country-specific GDP deflator. Statistical concept and methodology: Total wealth is calculated by summing up estimates of each component of wealth: produced capital, natural capital, human capital, and net foreign assets. The construction of the wealth accounts is guided by the concepts and methods of the System of National Accounts (SNA), the handbook developed by the UN Statistical Commission used by virtually all countries to compile their national economic accounts. While values for produced capital and net foreign assets are generally derived from widely used methods based on observed transactions for these assets, the value of natural capital and human capital must be estimated. The approach to asset valuation is based on the concept that the value of an asset should equal the discounted stream of expected net earnings (resource rents or wages) that it earns over its lifetime.