JHR's Baseball managers graph

A manager working his first job is shown as a blue bar. A manager working his second job is shown as a green bar, etc. Notice the small number of managers for the Dodgers recently and the large number of managerial changes for the Yankees. Managers are taken from Total Baseball's list of managers.
Do you think that changes look more common nowadays? Send me e-mail with observations about the graph or helpful comments about the graph's format.