Year	Percent
1991	30.196
1992	30.827
1993	32.237
1994	32.94
1995	34.147
1996	34.589
1997	35.732
1998	34.73
1999	36.617
2000	36.779
2001	36.835
2002	37.416
2003	38.027
2004	38.871
2005	41.228
2006	40.837
2007	43.078
2008	44.759
2009	45.337
2010	44.921
2011	44.375
2012	46.013
2013	47.962
2014	47.758
2015	48.792
2016	49.786
2017	49.7
2018	49.632
2019	49.574
2020	49.508
2021	49.447
2022	49.387