Year	Percent
1991	36.734
1992	36.847
1993	36.92
1994	37.117
1995	37.281
1996	37.392
1997	37.481
1998	37.585
1999	37.681
2000	37.834
2001	37.972
2002	38.135
2003	38.277
2004	38.521
2005	38.752
2006	39.094
2007	39.537
2008	39.953
2009	40.346
2010	40.713
2011	41.171
2012	41.658
2013	42.164
2014	42.674
2015	43.159
2016	43.606
2017	43.983
2018	44.354
2019	44.712
2020	45.055
2021	45.378
2022	45.686