Year	Percent
1991	26.706
1992	25.604
1993	24.244
1994	24.151
1995	23.787
1996	23.757
1997	23.387
1998	23.016
1999	21.987
2000	22.006
2001	22.586
2002	22.553
2003	22.926
2004	23.609
2005	24.9
2006	26.429
2007	29.438
2008	30.351
2009	33.576
2010	33.049
2011	32.446
2012	31.695
2013	30.763
2014	29.818
2015	29.343
2016	28.232
2017	28.582
2018	29.033
2019	29.486
2020	29.885
2021	30.235
2022	30.547