In this study, data were collected for 22 massive multi-input multi-output (MIMO) base stations in busy 5G sites over 15 months using a network monitoring tool. Logged precoding matrix index (PMI) data and time-averaged output power from the 5G base stations were used to obtain actual time-averaged output power statistics considering spatial distribution of power transmission corresponding to spreading of antenna beams in different directions over time. More than one billion output power samples were collected over the whole study period. The results show that the actual time-averaged output power per beam direction was significantly below the theoretical maximum power, with the mean and 95 th percentile values being 2.9% and 7.4%, respectively, of the theoretical maximum. At the busiest site the 95 th percentile and the maximum value were found to be 18.7% and 35.5%, respectively, of the theoretical maximum.