Year	Percent
1991	25.905
1992	26.519
1993	27.586
1994	28.364
1995	30.156
1996	30.122
1997	31.32
1998	31.428
1999	30.481
2000	31.03
2001	34.649
2002	35.628
2003	37.478
2004	39.076
2005	41.415
2006	42.107
2007	44.528
2008	45.789
2009	46.376
2010	48.238
2011	49.69
2012	50.947
2013	51.67
2014	51.832
2015	52.521
2016	52.378
2017	52.07
2018	52.097
2019	52.119
2020	52.144
2021	52.183
2022	52.226