Year	current US$
2000	5.4036844
2001	5.77955378
2002	6.39157432
2003	7.60444828
2004	8.35122772
2005	9.51820943
2006	9.87135756
2007	11.18079482
2008	13.00116663
2009	13.09768719
2010	12.96056235
2011	14.25403766
2012	13.72162175
2013	13.81786036
2014	13.60972935
2015	13.29649092
2016	13.12321946
2017	13.86188847
2018	14.73055759
2019	14.39092251
2020	15.1767712
2021	14.60488297