digraph {

    y2008;
    y2008 -> piano;

    y2008 -> y2010;
    y2010 -> drums;
    drums -> amped;

    y2010 -> y2012;
    y2012 -> killer_hamsters;
    amped -> killer_hamsters;
    y2012 -> drum_comps;
    drums -> drum_comps;

}