Mixed-drove spatio-temporal co-occurrence patterns (MDCOPs) represent subsets of object-types that are located together in space and time. Discovering MDCOPs is an important problem with many applications such as Planning battlefield tactics, and tracking predator-prey interactions. However, determining suitable interest measure thresholds is a difficult task In this paper, we define the problem of mining at most top-K% MDCOPs without using user defined thresholds and propose a novel at most top-K% MDCOP mining algorithm. Analytical and experimental results show that the proposed algorithm is correct and complete. Results show the proposed method is computationally more efficient than naive alternatives.