Year	Percent
1991	34.888
1992	35.496
1993	35.73
1994	36.18
1995	37.084
1996	37.135
1997	37.501
1998	38.039
1999	38.654
2000	38.559
2001	39.255
2002	39.389
2003	39.974
2004	39.052
2005	39.538
2006	40.793
2007	41.555
2008	41.732
2009	42.086
2010	41.958
2011	42.608
2012	43.364
2013	47.28
2014	47.565
2015	46.593
2016	47.131
2017	47.316
2018	47.831
2019	48.327
2020	48.927
2021	49.423
2022	49.942