The historical world presence metric shows the effective chart share occupied by world artists. “Effective chart share” is calculated by assigning song scores that are inversely correlated with song rank (i.e. score of 100 for rank 1, score of 99 for rank 2, and so on) and then calculating a total score for world artists as a percentage of the highest score possible. Numbers closer to 100 indicate a larger world presence and numbers closer to 0 indicate a smaller world presence. Note that the “world” genre consists of songs from international artists that reflect international genres that are not covered by the other genres studied- i.e. country, electronic, hip hop, pop, and rock.