Year	Percent
1991	31.051
1992	29.878
1993	28.84
1994	32.906
1995	33.195
1996	33.644
1997	34.578
1998	34.21
1999	34.744
2000	36.271
2001	37.053
2002	37.274
2003	37.138
2004	36.386
2005	37.125
2006	37.807
2007	36.117
2008	37.119
2009	37.268
2010	36.841
2011	36.556
2012	37.461
2013	36.981
2014	37.571
2015	37.896
2016	38.814
2017	36.54
2018	36.54
2019	36.623
2020	36.711
2021	36.785
2022	36.907