Year	Percent
1991	24.879
1992	25.938
1993	28.264
1994	33.514
1995	32.369
1996	31.692
1997	31.255
1998	28.085
1999	27.918
2000	29.848
2001	28.793
2002	25.805
2003	23.804
2004	24.168
2005	23.327
2006	19.202
2007	19.52
2008	25.992
2009	22.971
2010	21.132
2011	19.402
2012	18.962
2013	19.807
2014	17.821
2015	16.291
2016	16.167
2017	16.589
2018	16.287
2019	15.89
2020	15.543
2021	15.159
2022	14.788