1 Total greenhouse gas emissions and trends 3 Greenhouse gas inventory information, including the national system and the national registry 59 The most important greenhouse gas in Finland is carbon dioxide. The share of CO₂ emissions in total greenhouse gas emissions has varied from 80 per cent to 85 per cent. In absolute terms, CO₂ emissions have decreased by 12.7 million tonnes (i.e. 22 per cent) since 1990. Around 90 per cent of all CO₂ emissions originated from the energy sector in 2015. The amount of energy-related CO₂ emissions has fluctuated much according to the economic trend, the energy supply structure (including electricity imports and exports) and climate conditions. Methane emissions (CH) have decreased by 37 per cent from the 1990 level. This is mainly due to the improvements in waste sector and a contraction in animal husbandry in the agricultural sector. Correspondingly, emissions of nitrous oxide (N₂O) have also decreased by 27 per cent; the greatest decline occurred in 2009 when the implementation of a N₂O abatement technology in nitric acid production reduced emissions significantly. Another reason for the decrease of N₂O emissions is the reduced nitrogen fertilisation of agricultural fields. In 2015, the F-gas emissions (HFCs, PFCs and SF) were nearly 35 times higher than the emissions for 1995 (the