Year	Percent
1991	19.569
1992	16.879
1993	17.098
1994	18.081
1995	18.802
1996	17.537
1997	18.865
1998	17.393
1999	17.594
2000	19.397
2001	20.654
2002	21.953
2003	23.424
2004	24.275
2005	25.133
2006	26.178
2007	24.41
2008	28.21
2009	26.558
2010	25.661
2011	24.414
2012	22.41
2013	22.44
2014	21.817
2015	22.045
2016	21.976
2017	22.08
2018	22.294
2019	22.478
2020	22.681
2021	22.91
2022	23.067