![alt text][1]
\documentclass[border=5pt, varwidth]{standalone}
%\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{center}
\begin{tikzpicture}[>=latex, thick]
\draw[->] (0,0) -- (9cm,0) node [right] {$C$};
%Links
\draw (1.5,-2pt) -- (1.5,2pt) node[above]{$(X, X)$};
node[above left]{$(X, X)$} node[below=1ex]{Wert};
%Mitte
\draw[color=blue] (4.5,-2pt) -- (4.5,2pt) node[above, align=center, fill=lightgray, rounded corners, inner sep=2pt]{$(X, X) (X, Y)$ \\ und \\ $(Y, X) (Y, Y)$};
Y)$} node[below=1ex]{Wert};
%Rechts
\draw (7.5,-2pt) -- (7.5,2pt) node[above]{$(Y, Y)$};
node[above right]{$(Y, Y)$} node[below=1ex]{Wert};
\end{tikzpicture}
\end{center}
\end{document}
[1]: http://texwelt.de/wissen/upfiles/Namenlos-11e4yyy_27.pnghttp://texwelt.de/wissen/upfiles/Namenlos-11e4yyy_28.png
