IEA (2021), Low- and zero-carbon fuel shares in international shipping, 2020 and 2030 in the Net Zero Scenario, IEA, Paris https://www.iea.org/data-and-statistics/charts/low-and-zero-carbon-fuel-shares-in-international-shipping-2020-and-2030-in-the-net-zero-scenario, Licence: CC BY 4.0