Year	Percent
1991	24.741
1992	24.406
1993	23.165
1994	22.564
1995	23.029
1996	23.921
1997	23.9
1998	24.31
1999	24.229
2000	24.617
2001	25.365
2002	25.655
2003	26.085
2004	26.579
2005	26.528
2006	26.592
2007	27.071
2008	27.272
2009	26.648
2010	26.886
2011	27.376
2012	27.68
2013	28.322
2014	28.808
2015	29.397
2016	29.555
2017	29.572
2018	29.915
2019	30.304
2020	30.701
2021	31.097
2022	31.468