Year	Percent
1991	33.622
1992	37.52
1993	40.535
1994	39.882
1995	38.847
1996	42.772
1997	39.791
1998	37.594
1999	37.99
2000	38.441
2001	39.249
2002	40.208
2003	41.098
2004	41.694
2005	41.549
2006	41.582
2007	42.1
2008	41.768
2009	42.36
2010	43.832
2011	45.117
2012	44.217
2013	45.533
2014	46.652
2015	47.865
2016	48.39
2017	48.895
2018	49.426
2019	49.888
2020	50.393
2021	50.84
2022	51.258