Year	Percent
1991	38.566
1992	39.595
1993	38.265
1994	39.505
1995	38.866
1996	39.254
1997	41.149
1998	37.353
1999	34.355
2000	29.283
2001	24.157
2002	29.08
2003	28.375
2004	25.074
2005	25.053
2006	26.292
2007	29.446
2008	30.024
2009	21.205
2010	19.193
2011	20.899
2012	22.646
2013	27.206
2014	30.72
2015	31.003
2016	33.292
2017	33.55
2018	33.06
2019	32.416
2020	31.854
2021	31.223
2022	30.449