Year	Percent
1971	42.61687
1972	41.30665
1973	51.02366
1974	73.52161
1975	40.91919
1976	40.92366
1977	24.4429
1978	20.52701
1979	29.81405
1980	36.48038
1981	32.19646
1982	28.19121
1983	24.50125
1984	20.04579
1985	25.43453
1986	16.96495
1987	17.76404
1988	12.22367
1989	11.3243
1990	9.60248
1991	12.14452
1992	12.12931
1993	13.91328
1994	15.91661
1995	12.59951
1996	18.70946
1997	31.2818
1998	27.53837
1999	21.78939
2000	53.20934
2001	86.21138
2002	109.13727
2003	149.1265
2004	203.7382
2005	346.16006
2006	1378.20119
2007	1874.18863
2008	2370.94703
2009	2090.20427
2010	2347.84721
2011	3155.47506
2012	3636.70242
2013	3840.11855
2014	3375.12298
2015	3223.79027
2016	2209.66698