Net national income (NNI) is defined as gross national income minus the depreciation of fixed capital assets (dwellings, buildings, machinery, transport equipment and physical infrastructure) through wear and tear and obsolescence. This indicator is available in different measures: NNI in US dollars and US dollars per capita, at current prices and current PPPs; as an index (OECD nominal NNI per capita=100) and annual growth rates of NNI at constant prices. All OECD countries compile their data according to the 2008 System of National Accounts (SNA). The indicators based on nominal NNI are less suited for comparisons over time, as developments are not only caused by real growth, but also by changes in prices and PPPs.