Year	Percent
1991	33.907
1992	34.805
1993	34.818
1994	35.236
1995	35.412
1996	36.378
1997	36.652
1998	36.186
1999	37.402
2000	38.188
2001	38.726
2002	38.853
2003	39.245
2004	39.714
2005	40.284
2006	40.661
2007	41.024
2008	40.923
2009	40.871
2010	41.207
2011	41.816
2012	42.179
2013	42.114
2014	43.794
2015	44.74
2016	44.791
2017	44.427
2018	45.251
2019	45.997
2020	46.633
2021	47.234
2022	47.729