Year	current US$
1988	958.4605773118358
1989	770.9536649560873
1990	789.8503920644089
1991	1279.1806257384999
1992	1560.198707617415
1993	2079.6461744057433
1994	2468.819840565469
1995	2959.560851126761
1996	3393.503399172505
1997	3834.856217109568
1998	4127.320054236339
1999	4091.994006905032
2000	3994.8611438888934
2001	4021.177263232729
2002	4307.100826994911
2003	4458.108580375399
2004	4625.304246732653
2005	4630.009213533005
2006	4665.962801345467
2007	5162.032958803581
2008	5957.696754115483
2009	7149.791498048403
2010	7695.245414572785
2011	7914.1095681644965
2012	8500.180562940295
2013	8255.20921055985
2014	7665.379691862562
2015	7802.751367697762
2016	8172.299475991326
2017	8679.89742212366
2018	9225.845154869012
2019	8925.421860170723
2020	5599.957522607335
2021	4136.146575160125
2022	3823.9380686054633
2023	3350.297104209614