Year	constant 2015 US$
1991	8080.523750068975
1992	8261.043584768095
1993	8554.674082904481
1994	16603.11787436875
1995	16367.197683125916
1996	16333.104530694998
1997	16552.614486900533
1998	16343.398883275762
1999	16632.64554158514
2000	17262.43595579819
2001	17659.515948083266
2002	17967.122610864393
2003	18316.887800832577
2004	18338.17510386512
2005	18892.28467998862
2006	19289.922736258526
2007	20282.255179318545
2008	20695.37475417647
2009	20805.04064805779
2010	21197.47987605833
2011	21651.571398248205
2012	22394.97900351692
2013	22499.539318508825
2014	22545.0175280604
2015	22930.04386651274
2016	23628.8514677699
2017	24602.071161560016
2018	25411.646473421737
2019	26119.900881410937
2020	26172.983918120426
2021	27189.759851525294
2022	27637.738921618613