Year	%
1988	42.03923
1989	28.37907
1990	26.79747
1991	38.29128
1992	25.82546
1993	41.55033
1994	39.01709
1995	22.24446
1996	16.49536
1997	17.18517
1998	13.56226
1999	19.29771
2000	13.39193
2001	15.33249
2002	10.89379
2003	14.99599
2004	10.96169
2005	11.61354
2006	11.16618
2007	13.63596
2008	10.43935
2009	10.61339
2010	9.713589
2011	8.935537
2012	6.59698
2013	9.022916
2014	9.580304
2015	8.868967
2016	8.834718
2017	8.253676