You are replacing the legend each time. Use the loop to build up your labels, but don't atually create the legend until you exit the for loop.
Another option is to use the 'DisplayName' name value pair in your plot command.
EC = [0.0052 0.0078 0.0104 0.0130 0.0156 0.0182 0.0208 0.0234 0.0260 0.0286];
I'm not sure you want to include a lenged label for every line in your plot. I don't see how that will clarify anything.