Year	Percent
1991	30.583
1992	29.065
1993	28.992
1994	29.541
1995	29.504
1996	32.057
1997	31.747
1998	32.066
1999	31.689
2000	31.706
2001	31.695
2002	35.516
2003	36.353
2004	40.98
2005	42.18
2006	43.272
2007	44.337
2008	45.771
2009	47.35
2010	47.745
2011	49.039
2012	48.994
2013	49.558
2014	49.995
2015	54.364
2016	56.317
2017	57.343
2018	58.839
2019	59.787
2020	60.834
2021	61.408
2022	62.015