Year	Percent
1991	12.967
1992	13.57
1993	18.215
1994	18.573
1995	18.549
1996	18.185
1997	20.573
1998	20.092
1999	22.749
2000	22.678
2001	21.05
2002	19.646
2003	19.131
2004	19.343
2005	18.432
2006	17.835
2007	17.969
2008	17.117
2009	14.901
2010	13.696
2011	13.544
2012	13.834
2013	13.641
2014	13.509
2015	13.896
2016	13.498
2017	13.72
2018	13.769
2019	13.682
2020	13.532
2021	13.385
2022	13.212