Year	Percent
1991	41.525
1992	40.636
1993	38.651
1994	38.16
1995	38.342
1996	36.324
1997	33.521
1998	32.674
1999	31.837
2000	30.214
2001	29.185
2002	28.454
2003	28.54
2004	28.014
2005	29.96
2006	26.469
2007	24.79
2008	25.139
2009	23.855
2010	22.471
2011	22.213
2012	21.801
2013	21.335
2014	20.333
2015	20.508
2016	19.342
2017	18.221
2018	17.925
2019	17.574
2020	17.33
2021	18.056
2022	20.706