Year	current US$
1992	2360
1993	2960
1994	3480
1995	4220
1996	5020
1997	5420
1998	5430
1999	5380
2000	5540
2001	5730
2002	6040
2003	6980
2004	9060
2005	11370
2006	12950
2007	14940
2008	17290
2009	17150
2010	17620
2011	17590
2012	17830
2013	18270
2014	18340
2015	17760
2016	16840
2017	16670
2018	18400
2019	19200
2020	19250
2021	20650
2022	22080
2023	22790