Year	Percent
1970-01-01	0.1173460000000000
1971-01-01	0.0970130000000000
1972-01-01	0.0830480000000000
1973-01-01	29.7919999999999980
1974-01-01	26.6914000000000000
1975-01-01	0.0656350000000000
1976-01-01	2.8761400000000004
1977-01-01	8.7832100000000000
1978-01-01	14.9075000000000000
1979-01-01	14.6715000000000000
1980-01-01	13.1979000000000000
1981-01-01	14.8162000000000000
1982-01-01	22.4036000000000000
1983-01-01	32.0608000000000000
1984-01-01	38.0977000000000000
1985-01-01	45.0988000000000000
1986-01-01	53.8400000000000000
1987-01-01	54.8420000000000000
1988-01-01	53.2350000000000000
1989-01-01	48.9491000000000000
1990-01-01	39.7393000000000000
1991-01-01	35.2440000000000000
1992-01-01	33.2712000000000000
1993-01-01	34.4058000000000000
1994-01-01	33.7775000000000000
1995-01-01	33.4329000000000000
1996-01-01	30.4200000000000000
1997-01-01	29.0584000000000000
1998-01-01	33.5395000000000000
1999-01-01	31.9023000000000000
2000-01-01	27.9177000000000000
2001-01-01	28.5555000000000000
2002-01-01	28.2376000000000000
2003-01-01	26.0273000000000000
2004-01-01	22.0460000000000000
2005-01-01	16.2314000000000000
2006-01-01	13.2880000000000000
2007-01-01	12.3389000000000000
2008-01-01	11.4090000000000000
2009-01-01	16.0810000000000000
2010-01-01	14.5638000000000000
2011-01-01	12.8104000000000000
2012-01-01	12.7726000000000000
2013-01-01	9.8820500000000000
2014-01-01	7.1555700000000000
2015-01-01	9.3400100000000010
2016-01-01	10.4094000000000000