Year	%
1988	43.12139
1989	63.88462
1990	35.2468
1991	29.62195
1992	74.74312
1993	40.89476
1994	67.46773
1995	43.44396
1996	31.41437
1997	46.26048
1998	46.51831
1999	43.00703
2000	36.42699
2001	38.62934
2002	36.75239
2003	38.38314
2004	33.48194
2005	35.23465
2006	33.70553
2007	34.42773
2008	38.6771
2009	36.61477
2010	34.32266
2011	35.79589
2012	33.58842
2013	34.4612
2014	32.66417
2015	32.07624
2016	30.42276
2017	26.86516