Year	Percent
1991	74.614
1992	76.521
1993	78.52
1994	78.734
1995	78.981
1996	78.471
1997	78.768
1998	79.514
1999	79.491
2000	79.161
2001	79.696
2002	80.383
2003	80.588
2004	80.68
2005	80.566
2006	80.557
2007	80.072
2008	79.614
2009	76.449
2010	72.367
2011	69.857
2012	65.61
2013	65.075
2014	64.305
2015	63.191
2016	62.865
2017	62.843
2018	62.492
2019	62.079
2020	61.572
2021	60.94
2022	60.35