Year	Percent
1991	38.18976
1992	38.38327
1993	37.63651
1994	37.32665
1995	37.37145
1996	38.38012
1997	37.0798
1998	34.64978
1999	35.06708
2000	35.94234
2001	36.94085
2002	38.82528
2003	37.35999
2004	34.92789
2005	33.10906
2006	35.62282
2007	33.99241
2008	34.26709
2009	35.49536
2010	36.4516
2011	35.30315
2012	37.00501
2013	34.38296
2014	28.72954
2015	28.7221
2016	27.35428
2017	31.98484
2018	30.67284
2019	29.46628