Year	Percent
1991	21.316
1992	21.438
1993	20.022
1994	19.194
1995	18.319
1996	18.208
1997	18.621
1998	18.487
1999	18.464
2000	18.839
2001	19.571
2002	21.715
2003	23.436
2004	24.47
2005	24.167
2006	26.133
2007	30.211
2008	31.258
2009	30.585
2010	30.355
2011	29.756
2012	31.899
2013	34.879
2014	37.871
2015	40.333
2016	39.662
2017	38.753
2018	37.671
2019	36.693
2020	35.899
2021	35.375
2022	35.368