Year	Percent
1971	50.12167
1984	77.5453
1985	80.26324
1986	80.6254
1987	80.60278
1988	81.24448
1989	82.18088
1990	85.28751
1991	88.75824
1992	91.94018
1993	97.15077
1994	95.04279
1995	98.78132
1997	96.79542
2000	91.71146
2001	95.46213
2002	95.57446
2003	92.15615
2004	102.65369
2005	105.71237
2006	98.24512
2007	94.56649
2008	97.68463
2009	102.36383
2010	104.28722
2011	103.68998
2012	101.75152
2015	101.53143