Year % of tax revenue 1990 4.164624383230402 1991 1.6682072274307846 1992 1.0752688172043012 1993 0.06531154753993171 1995 0.006748605991074968 1996 0.0038401572928427148 1997 0.002806781183338947 2006 0.005602515529472734 2007 0.006483975738141692 2016 0.18255321880343495 2017 0.17843255351116083 2018 0.15135707952014607 2019 0.13255260712252176 2020 0.16554909045474797 2021 0.17128297500365988 2022 0.12806316622618968