Year	Percent
1991	51.698
1992	55.281
1993	58.387
1994	60.688
1995	62.318
1996	64.101
1997	66.243
1998	67.244
1999	68.162
2000	68.657
2001	70.184
2002	71.17
2003	71.961
2004	72.981
2005	74.488
2006	75.389
2007	76.155
2008	76.888
2009	78.708
2010	78.793
2011	78.873
2012	79.67
2013	80.288
2014	80.651
2015	81.129
2016	81.888
2017	82.052
2018	82.383
2019	82.711
2020	83.027
2021	83.341
2022	83.646