Year	Percent
1991	21.635
1992	21.735
1993	25.442
1994	25.912
1995	28.299
1996	29.471
1997	29.939
1998	32.391
1999	34.156
2000	33.933
2001	37.036
2002	37.007
2003	38.662
2004	40.425
2005	40.564
2006	40.321
2007	40.737
2008	41.464
2009	44.691
2010	45.737
2011	44.025
2012	42.135
2013	44.422
2014	48.235
2015	49.385
2016	49.407
2017	50.288
2018	51.366
2019	52.415
2020	53.354
2021	54.296
2022	55.315