Year	constant 2015 US$
1995	448.7473656465451
1996	445.95735015811266
1997	440.12260023636094
1998	435.63198433482916
1999	437.05225924066343
2000	427.57275463709743
2001	429.0206262167629
2002	398.8912047878514
2003	386.70795944318047
2004	380.29206781787695
2005	371.8558875916276
2006	376.10032487580764
2007	381.78155889348267
2008	388.0633537117412
2009	404.255484409673
2010	393.6556029733741
2011	392.1597403627797
2012	392.7681098674901
2013	350.65979829737057
2014	337.32946317418083
2015	316.6221146862437
2016	314.2619477102086
2017	311.83577829601023
2018	306.24397924269635
2019	318.9033266741983
2020	310.8173865119282
2021	298.0558633482787
2022	295.09527691477626