Year	kg per 2015 US$ of GDP
1990	0.2180360576816762
1991	0.19802308357518175
1992	0.2050150526776235
1993	0.20812573527832137
1994	0.21587424169272215
1995	0.25101312358195305
1996	0.2440799864414711
1997	0.2633801191108812
1998	0.25409353671210766
1999	0.25355149165571533
2000	0.24776604755342693
2001	0.29219082397864365
2002	0.29951393028285134
2003	0.30006361704227485
2004	0.3040236396702611
2005	0.3057814371152566
2006	0.31462861651080704
2007	0.3109882134885717
2008	0.3210545465515946
2009	0.32892972504473456
2010	0.3515174839079112
2011	0.35517049619163404
2012	0.36212943733459535
2013	0.364639072963954
2014	0.362078333720977
2015	0.3748817403048795
2016	0.38812396444756186
2017	0.3934313363412546
2018	0.40125424495371653
2019	0.3591471640319436
2020	0.32037553791068174