Year	Percent
1991	42.238
1992	41.517
1993	38.699
1994	38.319
1995	41.374
1996	41.438
1997	41.286
1998	41.572
1999	40.096
2000	47.133
2001	41.705
2002	36.792
2003	38.439
2004	42.229
2005	44.059
2006	45.124
2007	47.909
2008	47.822
2009	43.856
2010	43.143
2011	45.642
2012	44.293
2013	42.992
2014	42.097
2015	43.209
2016	41.623
2017	41.759
2018	41.683
2019	41.489
2020	41.257
2021	40.891
2022	40.822