Digital competence (DC) is a broad set of skills, attitudes, and knowledge for confident, critical and responsible use of digital technologies in every aspect of life. DC is fundamental to all people in conducting a productive and fulfilling life in an increasingly digital world. However, prejudices, misconceptions, and lack of awareness reduce the diffusion of DC, hindering digital transformation and preventing countries and people from realising their full potential. Teaching Informatics in the curriculum is increasingly supported by the institutions but faces serious challenges, such as teacher upskilling and support, and will require several years to observe sizeable outcomes. In response, grassroots movements promoting computing literacy in an informal setting have grown, including EU Code Week, whose vision is to develop computing skills while promoting diversity and raising awareness of the importance of digital skills. Code Week participation is a form of public engagement that could be affected by socio-economic and demographic factors, as any other form of participation. The aim of the manuscript is twofold: first, to offer a detailed and comprehensive statistical description of Code Week's participation in the EU Member States in terms of penetration, retention, demographic composition, and spatial distribution in order to inform more effective awareness-raising campaigns; second, to investigate the impact of socio-economic factors on Code Week involvement. The study identifies a strong negative correlation between participation and income at different geographical scales. It also suggests underlying mechanisms driving participation that are coherent with the "psychosocial" and the "resource" views, i.e. the two most widely accepted explanations of the effect of income on public engagement.