Year	current US$
2000	14.07812588
2001	12.95383487
2002	11.31067187
2003	9.43553574
2004	11.83134555
2005	12.39210771
2006	13.45500421
2007	16.22649414
2008	16.91760261
2009	17.53996334
2010	19.97402975
2011	21.64973711
2012	23.2151377
2013	23.67728773
2014	22.50520884
2015	25.97947982
2016	23.66206492
2017	28.86458832
2018	29.11010733
2019	23.22974086
2020	25.12017231
2021	30.54369291