Year	% of revenue
1972	24.33823529411766
1973	18.64907101927418
1974	18.433179723502306
1975	14.941395552634477
1976	16.15137033063495
1977	18.608198284080096
1978	18.538296007013603
1980	25.156436757364816
1981	19.65721304153639
1982	17.281321421151066
1983	14.626487718409745
1984	14.515795994218477
1985	17.324193957857307
1986	19.943094999736555
1987	21.82367277736566
1988	22.378429194086024
1989	25.13919705279021
1990	22.810491575473318
1991	22.97986154814344
1992	25.81766215206734
1993	25.011208416773727
1994	18.919826500629654
1995	3.5682922272047835
1996	3.5735527915458714
1997	3.5981888745148773
1998	3.745211230648124
1999	3.7688335358444713
2000	3.435269121813031
2001	3.348539657020364
2002	4.301950277275843
2003	3.374500587544066
2004	0.7071640805546385
2005	0.7178127014030043
2006	0.1118088672741867
2007	0.38372719920927306
2008	0.04058677615259602
2009	0.0031870139803679936
2014	0.9517794606243827