Thanks for your comment. I agree that one can also look at corporate profits directly instead of profits as a share of GDP. I redid the calculations and still can't find any correlationor causation of corporate tax rates with corporate profits. I looked at corporate profit growth instead of corporate profits directly, since corporate tax rates are somewhat stationary and need to be compared with a stationary variable in order to avoid drawing th wrong conclusions. Corporate profits have a trend component so in order to fettend it one can look at corporate profits as share of GDP or simple annual growth rates. In both cases there is no correlation or causation.