I have a simple example where the line styles in the diagram don't match the line styles in the key. The latter is correct.
Using Texlive 2015 just installed. tlmgr says no updates of pgfplots
avail.
\documentclass{article}
\usepackage{graphicx}
\usepackage{xcolor}
\usepackage{tikz,pgfplots}
\pgfplotsset{compat=1.12}
\begin{document}
\begin{figure*}
\begin{tikzpicture}
[line join=round]
\begin{axis}[legend style={at={(1,0.7)},anchor=west},
ylabel={I don't know what this is},
x tick label style={/pgf/number format/.cd,
use comma,
1000 sep={}}]
\addplot table [ x=Year, y=CC_IHW, col sep=comma, mark=none] {numbers.csv};
\addplot table [ x=Year, y=CC_W, col sep=comma, mark=none] {numbers.csv};
\addplot table [ x=Year, y=ML_IHW, col sep=comma, mark=none] {numbers.csv};
\addplot table [ x=Year, y=ML_W, col sep=comma, mark=none] {numbers.csv};
\addplot table [ x=Year, y=MS_IHW, col sep=comma, mark=none] {numbers.csv};
\addplot table [ x=Year, y=MS_W, col sep=comma, mark=none] {numbers.csv};
\legend{CCIHW,CCW,MLIHW,MLW,MSIHW,MSW}
\end{axis}
\end{tikzpicture}
\end{figure*}
\end{document}