Year	Percent
1991	26.862
1992	24.326
1993	25.03
1994	25.044
1995	24.9
1996	26.209
1997	25.677
1998	25.229
1999	25.246
2000	24.597
2001	23.861
2002	22.745
2003	22.638
2004	23.08
2005	25.188
2006	25.784
2007	26.415
2008	27.409
2009	28.326
2010	28.562
2011	28.072
2012	29.514
2013	28.852
2014	29.208
2015	29.855
2016	30.249
2017	30.354
2018	30.528
2019	30.711
2020	30.927
2021	31.15
2022	31.354