Year	Percent
1991	60.48
1992	50.026
1993	42.315
1994	36.452
1995	35.917
1996	37.673
1997	40.488
1998	43.398
1999	40.95
2000	38.232
2001	41.346
2002	41.23
2003	38.965
2004	39.483
2005	38.425
2006	38.718
2007	39.718
2008	44.298
2009	45.59
2010	47.154
2011	47.41
2012	48.788
2013	50.197
2014	51.24
2015	53.437
2016	54.142
2017	54.272
2018	55.353
2019	56.275
2020	57.334
2021	58.23
2022	59.156