Year	US Dollars
1996	4.71
1997	5
1998	5.39
1999	5.58
2000	6.06
2001	6.54
2002	7.44
2003	8.18
2004	8.6
2005	9.36
2006	10.53
2007	11.96
2008	13.96
2011	14.76
2012	16.5
2013	17.61
2014	18.6
2015	19.1
2016	20.22