Year	Percent
1991	44.87
1992	45.042
1993	44.222
1994	43.59
1995	42.884
1996	40.662
1997	40.05
1998	40.255
1999	38.888
2000	40.065
2001	38.485
2002	39.915
2003	42.112
2004	43.334
2005	39.87
2006	38.172
2007	41.432
2008	40.094
2009	39.397
2010	38.352
2011	38.815
2012	37.493
2013	38.836
2014	39.071
2015	37.32
2016	30.793
2017	30.711
2018	30.648
2019	30.586
2020	30.524
2021	30.462
2022	30.4