Year	Percent
1991	48.28098
1992	46.5838
1993	45.19023
1994	43.61721
1995	41.89996
1996	40.2062
1997	38.49233
1998	36.11897
1999	33.7108
2000	31.28401
2001	31.14647
2002	30.79316
2003	30.41267
2004	29.97307
2005	29.73752
2006	29.28997
2007	28.92118
2008	28.69033
2009	28.51799
2010	28.11114
2011	27.72578
2012	27.36773
2013	31.39217
2014	29.32094
2015	24.47833
2016	20.07121
2017	21.35394
2018	22.59058
2019	21.85967