Since the CBO and most other data sources stop their analysis of effective tax rates in 1979, here is a similar analysis as my last using data from Piketty and Saez (two well know liberal economists that are very much in favor in much higher taxes).
My first chart here simply their own computed effective tax rates (less the estate tax component).
Note that, even here, you need to go up to beyond the 99.5 percentile to find any sign of cuts in the effective tax rate.