Year	Percent
1991	41.045
1992	42.588
1993	43.125
1994	42.96
1995	43.236
1996	43.159
1997	44.233
1998	44.178
1999	44.399
2000	42.69
2001	40.988
2002	39.149
2003	36.952
2004	34.826
2005	34.143
2006	38.681
2007	39.481
2008	40.44
2009	41.053
2010	42.07
2011	39.786
2012	38.402
2013	41.434
2014	43.602
2015	47.073
2016	48.031
2017	48.191
2018	48.312
2019	48.407
2020	48.506
2021	48.611
2022	48.717