Despite this, Icelanders emitted 16.9 tonnes of CO2 per capita in 2016, the highest in EFTA, mainly resulting from transport and aluminium smelting. Nevertheless, in 2010, Iceland was reported by ''Guinness World Records'' as "the Greenest Country", reaching the highest score by the Environmental Sustainability Index, which measures a country's water use, biodiversity and adoption of clean energies, with a score of 93.5/100.