Year	Percent
1991	32.508
1992	30.497
1993	34.268
1994	36.301
1995	40.116
1996	39.119
1997	41.743
1998	40.042
1999	42.124
2000	38.256
2001	39.323
2002	38.796
2003	37.268
2004	41.142
2005	39.666
2006	43.352
2007	43.547
2008	44.046
2009	45.64
2010	46.625
2011	48.151
2012	48.985
2013	50.384
2014	51.235
2015	51.697
2016	53.953
2017	54.792
2018	56.124
2019	57.824
2020	59.045
2021	60.306
2022	61.388