This paper presents the results of a research effort aimed at the development of a novel tool for synthesizing RNAV approach trajectories that minimize a cumulative noise criterion, taking into account the total noise effect of all flight movements aggregated over a period of one year. This new multi-event trajectory optimization framework is an extension of a tool called NOISHHH developed previously for the design of single-event noise abatement trajectories. Application of the adapted optimization framework to the design of noise abatement RNAV approach routes at Rotterdam The Hague airport in the Netherlands reveals a significant improvement in terms of the number of people highly annoyed due to annual noise exposure in comparison to the existing situation.