Year	Percent
1991	24.124
1992	27.568
1993	31.61
1994	32.031
1995	30.537
1996	30.529
1997	29.819
1998	28.532
1999	30.495
2000	28.807
2001	27.958
2002	25.787
2003	24.661
2004	23.965
2005	23.316
2006	21.461
2007	21.741
2008	24.477
2009	24.425
2010	23.786
2011	22.58
2012	22.459
2013	22.388
2014	21.402
2015	21.866
2016	20.515
2017	20.907
2018	20.508
2019	20.065
2020	19.612
2021	19.181
2022	18.762