The structure of government revenues shows the sources from which governments collect their revenues, and how these change over time. Taxes are the most significant source of government revenues in all OECD countries (Figure ). In 2021, the most recent year for which data are available for all countries, 60.6% of revenues in OECD countries were raised through taxes. In most OECD countries, taxes accounted for more than 50% of total government revenues. However, there was still a wide variation in their relative importance. The countries raising the highest share of revenues from taxes in 2021 were Denmark (88.5%) and New Zealand (82.8%), while Costa Rica had the lowest share (40.5%). The second most important source of revenues for OECD governments is social contributions, that is, payments into social insurance schemes. On average, these formed 24.7% of government revenues in OECD countries in 2021. Most countries which collected a relatively low share of their revenues from tax instead collected a relatively high share from social contributions, for example the Czech Republic (40.0% of revenues from social contributions) and the Slovak Republic (38.8%). OECD countries also collect a small proportion of their revenues from sales of goods and services (7.9% on average) and from grants and other sources (6.8%).