Year	Percent
1981	54.73914
1982	53.25651
1983	54.37709
1984	47.89826
1985	52.57845
1986	50.98637
1987	49.12477
1988	48.59305
1989	48.39091
1990	49.49125
1991	58.66606
1992	63.83134
1993	59.9453
1994	52.69945
1995	51.9247
1996	51.16537
1997	54.02899
1998	49.06191
1999	45.48546
2000	44.66602
2001	42.34057
2002	38.69237
2003	37.28506
2004	38.67975
2005	41.1745
2006	42.52417
2007	42.26501
2008	45.18456
2009	45.88269
2010	41.44682
2011	41.24996
2012	44.33094
2013	41.23951
2014	38.52045
2015	36.05698
2016	34.69888
2017	33.77928
2018	31.2188
2019	33.63333
2020	35.55827
2021	37.57912
2022	37.63903