Year	Percent
1991	57.441
1992	57.483
1993	57.21
1994	56.619
1995	56.519
1996	54.413
1997	56.034
1998	55.247
1999	55.271
2000	54.179
2001	53.206
2002	46.764
2003	45.425
2004	45.12
2005	43.337
2006	44.358
2007	44.303
2008	43.993
2009	43.193
2010	43.471
2011	43.166
2012	43.466
2013	43.098
2014	43.334
2015	42.547
2016	42.259
2017	42.321
2018	42.066
2019	41.574
2020	41.221
2021	40.888
2022	40.576