Year	Percent
1971	19.91961
1972	24.65369
1973	27.91518
1974	31.54376
1975	35.33284
1976	38.87931
1981	76.73475
1982	87.43371
1983	93.50896
1984	122.30775
1985	79.46557
1986	71.03969
1987	68.35606
1988	62.58982
1989	47.49167
1991	62.61452
1992	55.2596
1993	58.13459
1994	55.75488
1997	58.42347
1998	48.48839
1999	57.38078
2000	49.54374
2001	54.94683
2002	58.97959
2004	57.36355
2005	54.01245
2006	70.46604
2007	80.43243
2009	98.93668
2010	86.12348
2012	77.23721
2013	72.38466