Add the option to label lines directly
A legend need not to be in a small box tucked into the corner of the chart. Direct labeling allows a reader to identify the lines quickly and focus on comparing and contrasting the patterns.
TIP: read the book 'The Wall Street Journal - Guide to Information Graphics' by Dona M. Wong. Has an interesting point on 3D charts!
Or use the renderer function:
One way to do that is to display the data label of the last point only.