Year % of tax revenue 1972 4.872881355932203 1973 4.838263754492673 1974 5.411602843384545 1975 5.708204334365325 1976 4.8784692294431995 1977 8.285163776493256 1978 6.373682857877153 1979 5.081127241673783 1980 3.493907851206326 1981 4.918620491862049 1982 5.239813117274824 1983 3.482509485940018 1984 2.592515157850721 1985 3.016722408026756 1986 4.062870699881376 1987 4.130351437699681 1988 6.297198538367844 1989 9.538012051859516 1990 4.016035196387739 1991 4.075930957939454 1992 2.6096297232402375 1993 3.718818014398125 1994 0.7654732271527764 1995 4.473149239445978 1996 4.209925918884234 1997 3.014915324303596 1998 2.828274019091671 1999 2.785141806368081 2000 3.103569874911105 2001 3.0286622189901036 2002 2.8906691134952007 2003 2.63993661270889 2004 3.5110373582853396 2005 4.3199256868515965 2006 4.6116243555647705 2007 4.431587644875193 2008 3.4820897261115014 2009 3.10022663874633 2010 3.8140456320749028 2011 4.431016001963155 2012 4.2144058348522755 2013 4.689057255894319 2014 3.91569702524561 2015 4.075938285701838 2016 3.784050975567493 2017 3.907657373437888 2018 4.120937123572239 2019 3.8886506263588263 2020 3.5525743684576088 2021 3.5435749899653652 2022 4.223527478662194