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Income tax expense (benefit) statutory rate versus actual rate (Details 6) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Computed tax at federal statutory rate |  |  |
Computed tax at federal statutory rate | $ 97,997 | $ 99,775 | $ 83,674
Federal statutory rate | 21.00% | 21.00% | 21.00%
Increases (reductions) resulting from: |  |  |
State income taxes, net of federal income tax | $ 19,496 | $ 17,845 | $ 14,029
State income tax, rate | 4.20% | 3.80% | 3.50%
Federal renewable energy credit | $ (13,914) | $ (16,009) | $ (15,843)
Federal renewable energy credit, rate | (3.00%) | (3.40%) | (4.00%)
Tax compliance and uncertain tax positions | $ (477) | $ (3,543) | $ (2,739)
Tax compliance and uncertain tax positions, rate | (0.10%) | (0.70%) | (0.70%)
Excess deferred income tax amortization | $ (10,295) | $ (12,517) | $ (11,904)
Excess deferred income tax amortization, rate | (2.20%) | (2.60%) | (3.00%)
Other | $ (3,887) | $ (961) | $ (3,938)
Other, rate | (0.80%) | (0.30%) | (0.90%)
Income taxes | $ 88,920 | $ 84,590 | $ 63,279
Total income tax expense, rate | 19.10% | 17.80% | 15.90%

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