Year	Percent
1991	33.714
1992	33.837
1993	33.764
1994	33.533
1995	33.271
1996	33.334
1997	33.157
1998	32.878
1999	32.682
2000	32.742
2001	32.949
2002	33.014
2003	33.007
2004	35.947
2005	34.319
2006	32.729
2007	31.166
2008	29.634
2009	28.139
2010	26.69
2011	25.295
2012	23.944
2013	22.641
2014	21.438
2015	20.874
2016	20.372
2017	20.246
2018	20.109
2019	19.965
2020	19.747
2021	19.532
2022	19.312