Year	Percent
1991	29.175
1992	29.318
1993	28.454
1994	27.726
1995	26.871
1996	28.208
1997	29.788
1998	30.481
1999	32.62
2000	34.262
2001	36.581
2002	35.142
2003	38.535
2004	39.521
2005	41.543
2006	43.01
2007	43.403
2008	42.947
2009	42.418
2010	43.001
2011	44.095
2012	45.202
2013	45.797
2014	46.151
2015	46.747
2016	47.311
2017	47.608
2018	47.872
2019	48.105
2020	48.317
2021	48.512
2022	48.688