Year	US Dollars
1960	5.37359
1961	5.81627
1962	7.52016
1963	6.75021
1964	7.4868
1965	8.14703
1966	5.18958
1967	5.07793
1968	4.0299
1969	4.27664
1970	4.43436
1971	5.17889
1972	5.72029
1973	6.35676
1974	8.02239
1975	11.19521
1976	8.16402
1977	10.7023
1978	12.61791
1979	16.03536
1980	16.14568
1981	14.28192
1982	12.2778
1983	10.69809
1984	10.05092
1985	9.91427
1986	13.28789
1987	20.59544
1988	16.34753
1989	20.96457
1990	24.89167
1991	12.77813
1992	7.00506
1993	4.49258
1994	5.89733
1995	4.49917
1996	3.7662
1997	3.52236
1998	2.76759
1999	2.86932
2000	3.67037
2001	4.9223
2002	22.76661
2003	101.81308
2004	35.01101
2005	33.2766
2006	37.63581
2007	22.36329
2008	28.38406
2009	36.75652
2010	52.47152
2011	80.49696
2012	40.0881
2013	35.17573
2014	31.56443
2015	33.04414
2016	25.81733
2017	27.2016
2018	28.86872
2019	31.24588
2020	36.42407
2021	36.87067