The growing commitment of the European Union to the promotion and protection of the rights of children and adolescents confirms the continuous activity of collecting and organising data in the area of children and adolescents in the EU countries that the National Centre has carried out, within the framework of its institutional tasks. The results of this activity are published in the National Centre's notebooks under the title European numbers. For each of the topics investigated, a battery of indicators is elaborated, useful to make comparisons on different levels: between single countries, between the same countries and the average EU reference, and finally, regarding the situation of the same country over time. The changes in the geopolitical structure of the EU lead to continuous changes in the structure of these data, which are naturally multiplied by the progressive extension of member countries.