Year	Percent
1988	3.9683
1989	4.47512
1990	4.12384
1991	3.66404
1992	3.53017
1993	2.64165
1994	3.62652
1995	5.12678
1996	4.09966
1997	4.05827
1998	3.93444
1999	4.79729
2000	6.22909
2001	7.80107
2002	7.20436
2003	8.50007
2004	8.68351
2005	8.86336
2006	8.90436
2007	8.16786
2008	7.7778
2009	4.10497
2010	3.51094
2011	3.68837
2012	4.13897
2013	4.30885
2014	4.38064
2016	5.29015