Farbe bei Legendeneinträge bei pgfplots

\documentclass[fontsize=12pt,paper=a4]{scrartcl}
\usepackage{pgfplots,filecontents}
\pgfplotsset{compat=newest}
\usepgfplotslibrary{dateplot}
\usepackage{tikzscale}  
\begin{filecontents}{external-debt.csv}
Quarter,Monetary authorities Short-term debt,General government,General government Short-term debt,General government Long-term debt,Deposit money banks Short-term debt,Deposit money banks Long-term debt,Other sectors,Direct investment,Total external debt,Total external debt-Direct investment,External debt position to GDP-ratio
2000-01-01,9594,131965,13816,118149,50818,133295,203488,13658,542818,13658,82.6
2000-04-01,13562,140222,18081,122141,78429,224328,149843,12981,619365,12981,92.6
2013-10-01,29439,556918,0,556918,125319,21850,10079872,1372697,12328310,1372697,613.3
2014-01-01,26667,514831,0,514831,129525,26652,9921453,1337141,12095886,1337141,592.3
\end{filecontents}

\begin{filecontents}{external-debt.tikz}
\begin{tikzpicture}
\sffamily
  \begin{axis}[
   date ZERO=2000-01-01,
     date coordinates in=x,
     no marks,
     width=15cm,height=8cm,
     enlargelimits=false,
     xticklabel={\tiny\year},
     xtick={2000-1-1,2001-01-01,2002-01-01,2003-01-01,2004-01-01,2005-01-01,2006-01-01,2007-01-01,2008-01-01,2009-01-01,2010-01-01,2011-01-01,2012-01-01,2013-01-01,2014-01-01},
     xtick pos=left,
     xtick align=outside,
     ymin=0,ymax=16 000 000,
     % assume math mode: nicht überprüfen ob der Mathemodus an ist
     % int detect: keine Nachkommastellen für ganze Zahlen anzeigen
     % 1000 sep={\,}: Kleiner Abstand zwischen 3er-Kolonnen
     yticklabel={\pgfmathprintnumber[assume math mode,int detect,1000 sep={\,}]{\tick}},
     % y-Achse nicht skalieren, sondern die tatsächliche Zahl im \tick angeben
     scaled y ticks=false,
     ytick style={draw=none},
     yticklabel pos=right,
     ymajorgrids=true,
    legend style={
      draw=none,
      legend cell align=left,
      %at={(0.00,1.4)},
      at={(1.15,1.05)},
       anchor=north west,
      legend image code/.code={
        \filldraw[##1] (-.5ex,-.5ex) rectangle (1ex,1ex);
      }
    }
    ]

    \addplot table[col sep=comma,x=Quarter,y={Monetary authorities Short-term debt}] {external-debt.csv};
    \addlegendentry{Monetary authorities Short-term debt};
     \addplot table[col sep=comma,x=Quarter,y={General government}] {external-debt.csv};
        \addlegendentry{General government};
         \addplot table[col sep=comma,x=Quarter,y={General government Short-term debt}] {external-debt.csv};
            \addlegendentry{General government Short-term debt};
             \addplot table[col sep=comma,x=Quarter,y={General government Long-term debt}] {external-debt.csv};
                \addlegendentry{General government Long-term debt};
                 \addplot table[col sep=comma,x=Quarter,y={Deposit money banks Short-term debt}] {external-debt.csv};
                    \addlegendentry{Deposit money banks Short-term debt};
                     \addplot table[col sep=comma,x=Quarter,y={Deposit money banks Long-term debt}] {external-debt.csv};
                        \addlegendentry{Deposit money banks Long-term debt};
                         \addplot table[col sep=comma,x=Quarter,y={Other sectors}] {external-debt.csv};
                            \addlegendentry{Other sectors};
                             \addplot table[col sep=comma,x=Quarter,y={Direct investment}] {external-debt.csv};
                                \addlegendentry{Direct investment};
                                 \addplot table[col sep=comma,x=Quarter,y={Total external debt}] {external-debt.csv};
                                    \addlegendentry{Total external debt};
                                     \addplot table[col sep=comma,x=Quarter,y={Total external debt-Direct investment}] {external-debt.csv};
                                        \addlegendentry{Total external debt-Direct investment};
                                         \addplot table[col sep=comma,x=Quarter,y={External debt position to GDP-ratio}] {external-debt.csv};
                                            \addlegendentry{External debt position to GDP-ratio};

  \end{axis}
\end{tikzpicture}
\end{filecontents}

\begin{document}
\begin{figure}
\begin{center}
\includegraphics[width=1.0\linewidth]{external-debt.tikz}
\end{center}
\label{Fig:interbankfinanzkredite}
\end{figure}    
\end{document}