In this paper the analysis of the spectrum occupancy in the TV band is provided based on the outdoor measurements campaigns carried out in Poznan, Poland in 2013 and 2014. The goal of this work is to discuss the stability and other important features of the observed spectrum occupancy in the context of outdoor Radio Environment Maps database deployment. Reliable deployment of these databases seems to be one of the critical points in practical utilization of the TV White Spaces for cognitive purposes inside buildings and in densely populated cities. The results obtained for outdoor scenario are briefly compared with the previous measurements conducted indoors in Barcelona, Spain, and in Poznan, Poland. ; Peer Reviewed ; Postprint (published version)