Year	% of tax revenue
1972	27.277514481305946
1973	29.330889092575617
1974	31.28390596745027
1975	29.18796138557638
1976	30.601659751037346
1977	31.98198198198198
1978	33.16126735493058
1979	35.641387972994195
1980	35.45479009687836
1981	36.13146791028203
1982	40.07309273640932
1983	43.53346080305927
1984	42.98608754665762
1985	41.05569948186529
1986	36.432425727221975
1987	36.297058467497884
1988	40.01126443255421
1989	41.081500646830534
1990	42.21769148788286
1991	39.46982055464927
1992	41.29413439635535
1993	39.55005843396962
1994	39.96223656961871
1995	39.61983281804649
1996	37.323850567115244
1997	20.05672417868116
1998	18.464316459151323
1999	16.54598882209461
2000	14.482952944491407
2001	13.922687454793861
2002	12.15255634536716
2003	10.816191108161911
2005	9.2064978112902
2006	8.819570710052185
2007	8.451741147022013
2008	8.2950162829078
2009	8.261856388721235
2010	8.860819302915282
2011	7.748081270714594
2012	8.83453082532763