Year	Percent
1978	18.48101
1979	17.55665
1980	13.13514
1981	17.95526
1982	19.2025
1983	19.97857
1984	27.0625
1985	20.60217
1986	15.09149
1987	15.73725
1988	20.28596
1989	16.06786
1990	10.32364
1991	26.82525
1992	30.48277
1993	29.41652
1994	29.34853
1995	28.49908
1996	26.07835
1997	23.90967
1998	24.38567
1999	25.16449
2000	19.95974
2001	20.39861
2002	21.655
2003	23.44768
2004	24.40159
2005	20.47155
2006	22.04191
2007	23.16519
2008	24.69316
2009	26.61082
2010	24.19156
2011	25.21788
2012	24.41434
2013	23.11824
2014	23.99037
2015	21.68114
2016	26.3385
2017	30.43858
2018	25.31049
2019	25.90362
2020	26.48339
2021	23.09328