Year	Percent
1987	36
1988	33.33333
1989	35.71429
1990	40
1991	45.76271
1993	36.92615
1996	49.43806
1997	38.68105
1998	45.49482
1999	39.66893
2000	34.73866
2001	31.71266
2002	27.55968
2003	25.41874
2004	23.05362
2005	22.91831
2006	19.5002
2007	18.6
2008	31.7
2009	46.6
2010	51.88083
2011	51.93184
2012	47.2