Year	Percent
1991	87.329
1992	87.265
1993	87.293
1994	87.618
1995	87.134
1996	86.879
1997	86.18
1998	85.759
1999	84.665
2000	84.047
2001	83.635
2002	83.203
2003	82.028
2004	80.731
2005	80.289
2006	78.711
2007	74.217
2008	71.503
2009	66.968
2010	62.513
2011	57.359
2012	52.093
2013	46.214
2014	37.209
2015	35.982
2016	35.406
2017	34.71
2018	33.975
2019	33.267
2020	32.58
2021	31.876
2022	31.112