Year	Percent
1991	40.19218
1992	40.36781
1993	40.2577
1994	40.53733
1995	39.73306
1996	38.96179
1997	38.71125
1998	38.24813
1999	38.05955
2000	37.75018
2001	37.41919
2002	36.95158
2003	36.46471
2004	36.27539
2005	35.7033
2006	35.3011
2007	34.8176
2008	34.39128
2009	33.88117
2010	33.83286
2011	32.85969
2012	31.8825
2013	31.29395
2014	30.70388
2015	30.21845
2016	29.8429
2017	29.47486
2018	28.99119
2019	28.83024