Year	Percent
1991	89.78088
1992	89.63902
1993	89.41996
1994	89.13786
1995	88.06721
1996	86.76853
1997	85.39669
1998	83.86347
1999	82.14097
2000	80.43305
2001	78.34518
2002	76.11242
2003	73.46147
2004	70.71911
2005	67.5202
2006	64.09168
2007	60.53176
2008	56.66341
2009	52.69426
2010	48.21623
2011	43.70838
2012	39.18327
2013	34.72371
2014	30.37531
2015	29.7458
2016	28.92888
2017	28.02316
2018	27.08124
2019	26.19575