Year	Percent
1991	70.823
1992	71.11
1993	70.564
1994	69.806
1995	68.563
1996	67.464
1997	66.233
1998	64.632
1999	63.18
2000	61.898
2001	59.854
2002	57.943
2003	56.099
2004	54.349
2005	53.137
2006	52.089
2007	51.633
2008	50.245
2009	49.555
2010	48.632
2011	47.601
2012	46.458
2013	45.255
2014	43.976
2015	42.75
2016	41.564
2017	40.948
2018	40.283
2019	39.647
2020	39.066
2021	38.547
2022	38.123