Year	% of expense
1972	48.8880652335063
1973	44.16715031921068
1974	26.569908079342042
1975	28.8981288981289
1976	33.25780641506762
1977	37.99585088325894
1978	46.206425153793575
1979	61.726374492331935
1980	57.88590604026845
1981	55.93119538862711
1982	56.07831916285154
1983	55.56036660171755
1984	56.40117140894465
1985	62.46249353336783
1986	66.97947634227587
1987	64.48432141107301
1988	57.47772856218584
1989	60.59455885593946
1990	52.71914710316605
1991	58.46240495635032
1992	51.09686466993889
1993	58.2300997395337
1994	59.874723655121585
1995	55.94115042740865
1996	60.495084685538316
1997	62.38271874318132
1998	63.19591480881803
1999	54.18626067756755
2000	56.62578518772278
2001	51.024463143951294
2002	47.53287477949997
2003	44.97889026410815
2004	44.4130355610803
2005	40.420009029110304
2006	38.1424911303406
2007	36.2691165159145
2008	36.72020681222427
2009	39.799578229082854