Time series analysis is the centerpiece of numerous research fields from stock analysis to topic mining. While the univariate case is still commonplace, there is an increasing need for tools providing features to study the relationships between multiple time series. Initially motivated by a interdisciplinary research agenda with sociologists and musicologists, we propose an extension of the famous stacked graph to display an overview of a set of multiple and item-set time series. This visualization allows the exploration of the general tendencies observed on a population and the comparison of patterns between groups. A proof-of-concept is presented on real-life data extracted from a recent study on the daily music listening behavior.