Year	Percent
1971	34.55967
1981	52.35496
1994	61.99568
1999	72.46719
2000	77.82426
2002	90.43287
2004	86.2749
2006	83.75366
2007	90.95272
2009	92.57041
2010	91.43552
2011	91.13156
2012	90.69498
2013	90.65205
2014	90.9116
2015	94.21953
2016	93.27347