Year	Percent
1991	31.242
1992	29.899
1993	27.23
1994	26.039
1995	26.549
1996	25.352
1997	25.219
1998	23.737
1999	22.744
2000	22.622
2001	25.34
2002	22.664
2003	22.602
2004	25.654
2005	24.192
2006	21.638
2007	21.805
2008	22.095
2009	19.372
2010	17.958
2011	19.064
2012	17.655
2013	17.14
2014	17.524
2015	17.47
2016	17.273
2017	17.491
2018	17.24
2019	16.737
2020	16.208
2021	15.559
2022	15.204