Year	Percent
1991	23.382
1992	24.449
1993	25.589
1994	25.243
1995	25.019
1996	23.819
1997	23.338
1998	22.252
1999	22.821
2000	22.623
2001	22.957
2002	21.989
2003	21.326
2004	20.536
2005	20.223
2006	21.207
2007	21.213
2008	21.242
2009	20.956
2010	21.712
2011	21.467
2012	21.389
2013	21.316
2014	21.611
2015	22.314
2016	22.422
2017	22.399
2018	22.398
2019	22.343
2020	22.304
2021	22.264
2022	22.229