d_avg distributions, defined as the average distance between pairs of orbits through the Galaxy from the present time (or t = 0 Gyr) until the close encounter time (τ_enc). The pink distribution refers to the whole integration time (1 Gyr), and the black distribution refers to close encounters with relative velocities within 0.2 Gyr and 100 pc distance. (A color version of this figure is available in the online journal.)