Year	% of total
1971	9.294224818264297
1972	9.957093557755629
1973	10.17917922927389
1974	9.31303685604501
1975	8.44204736784199
1976	9.06025946155513
1977	8.610537620591058
1978	8.968870163220092
1979	8.967922846890783
1980	8.979365787540523
1981	8.387755880279828
1982	7.8504438422045215
1983	7.773770181871385
1984	7.546618641586281
1985	7.400769022751671
1986	7.609523812704986
1987	7.282311981279313
1988	6.934366031122057
1989	6.862546863633526
1990	6.903459486716465
1991	6.752668157769048
1992	6.102430567634721
1993	6.643225124254981
1994	6.566011793365992
1995	8.93729635598505
1996	8.290844949752401
1997	7.685396370162959
1998	6.592101914608304
1999	5.541691497036037
2000	6.057241929774844
2001	6.325560279968352
2002	6.922504863625358
2003	6.98979239279108
2004	9.173357754551574
2005	10.06711977662891
2006	10.439420029981386
2007	9.856552097759652
2008	9.799409682055302
2009	9.287739043699546
2010	10.61036898312748
2011	12.582518770882926
2012	14.906838112441687
2013	14.881109123331926
2014	14.380616951892103