Year	Percent
1980	32.62947
1981	29.90199
1982	30.96557
1983	31.76333
1984	31.3214
1985	31.71801
1986	32.25582
1987	35.8221
1988	36.12264
1989	33.72298
1990	32.00794
1991	32.97698
1992	29.05517
1993	37.24808
1994	18.58226
1995	22.34434
1996	26.13181
1997	25.21073
1998	26.77442
1999	28.61224
2000	29.66089
2001	29.34634
2002	32.28718
2003	30.12818
2004	28.8733
2005	27.37668
2006	25.67388
2007	22.88249
2008	24.93236
2009	25.3093
2010	24.63214
2011	23.93141
2012	23.52929
2013	23.84929
2014	23.87344
2015	22.99484
2016	22.19291
2017	22.92624
2018	21.62944
2019	23.00254
2020	22.89243
2021	22.77413
2022	21.76209