Analysing the distribution of power among political actors is at the heart of political science. I propose a way of analysing changes to the institutional equilibrium of the EU institutions as well as changes in the relationship between the supranational level and the member states from a historical perspective. At the core of the paper is a new dataset that allows us to trace changes to the EU treaties from 1958 to date. The findings are largely in line with what we know from the existing literature: Supranational actors, namely the European Parliament and the Commission have gained power, while the intergovernmental mode of decision-making has subsequently become more limited, thereby weakening the Council. Additionally, the expanding number of policy areas has strengthened the supranational level. The specific contribution of this paper is the transparent and replicable way in which I am able to reveal and map these changes. The dataset could function as a starting point for both qualitative and quantitative studies of European Integration. The dataset is available from the author upon request and will be made public on his website in due time.