Year	Percent
1991	31.091
1992	29.128
1993	27.263
1994	25.69
1995	28.216
1996	30.176
1997	31.918
1998	32.393
1999	33.694
2000	34.734
2001	35.54
2002	36.611
2003	37.699
2004	38.934
2005	39.562
2006	40.093
2007	41.323
2008	39.466
2009	38.924
2010	41.67
2011	41.274
2012	42.089
2013	44.937
2014	45.968
2015	45.65
2016	46.695
2017	46.639
2018	47.231
2019	47.911
2020	48.602
2021	49.198
2022	49.814