From minute-by-minute and daily-averaged absorptions of cosmic radio wave noise, deduced from continuous riometer recordings during the last 20 years at Sanae, the annual temporal pattern of energetic (>40 keV) electron energy flux deposited per second into the atmosphere has been estimated. We conclude that the energy flux deposited per second is closely related to geomagnetic activity, both for auroral precipitation during magnetic active periods and for particles precipitated from the trapping regions. The average energy flux deposited per second is strongly peaked during the equinoxes and has a deep minimum during the summer and winter, related to the equinoctial effect of geomagnetic activity. No difference exists between the energy fluxes deposited per second during the illuminated Antarctic summer and the dark Antarctic winter. It follows then that the daytime deposited flux is larger than the nighttime averaged deposition of energetic electrons. The averaged electron energy flux deposited per second peaked during 1973--1975 and 1982--1984, years with persistent solar wind high-speed streams from low solar latitude coronal holes, and has a lower value in a year of solar polar magnetic reversal, i.e., in 1971 and in 1980, than during solar minimum activity in 1976 and 1986/1987. During the 20 years of investigation the solar flare events of August 1972 and October 1989 are outstanding in flux of electron precipitation, being ~3 orders of magnitude larger than the annually averaged flux. ¿ American Geophysical Union 1993