Year	Percent
1991	18.757
1992	18.526
1993	17.741
1994	18.081
1995	17.713
1996	18.317
1997	18.608
1998	23.283
1999	21.594
2000	20.411
2001	20.479
2002	20.632
2003	20.466
2004	21.427
2005	21.839
2006	22.118
2007	22.57
2008	22.513
2009	26.709
2010	30.08
2011	35.933
2012	41.512
2013	41.998
2014	42.807
2015	43.374
2016	44.142
2017	44.672
2018	45.465
2019	46.224
2020	46.994
2021	47.755
2022	48.467