I think it will be better if the behavior of the buttons "1985<<" and ">>2020" would step only one year rather than directly to the start (1985) or to the end (2020) of the whole series. Consider changing the label of the buttons to "-1year" and "+1year".
I think it will be better if the behavior of the buttons "1985<<" and ">>2020" would step only one year rather than directly to the start (1985) or to the end (2020) of the whole series. Consider changing the label of the buttons to "-1year" and "+1year".