Total revenue gathered from environmentally-related taxes, fees, charges, tradable permits, deposit-refund systems, environmentally motivated subsidies, and voluntary approaches used for environmental policy, as a percent of gross domestic product (GDP). The tax bases covered include:

• Energy products (including vehicle fuels);
• Motor vehicles and transport services;
• Measured or estimated emissions to air and water, ozone depleting substances, certain non-point sources of water pollution, waste management and noise, as well as management of water, land, soil, forests, biodiversity, wildlife, and fish stocks.