\documentclass[a4paper,11pt] {article}
\usepackage{amsmath,amsfonts,subfigure,graphicx}
\usepackage{geometry}
\geometry{hmargin=-0.5cm,vmargin=0cm}
\graphicspath{{dataGeneration/}}

\begin{document}
\pagestyle{empty}
  \centering
  \begin{tabular}{cc}
    Data set 1, 100\% & Data set 2, 100\%\\
  \includegraphics[width=9cm]{dataGeneration-Affy100} &
  \includegraphics[width=9cm]{dataGeneration-Illu100}\\
    Data set 1, 70\% & Data set 2, 79\%\\
  \includegraphics[width=9cm]{dataGeneration-Affy70} &
  \includegraphics[width=9cm]{dataGeneration-Illu79}\\
    Data set 1, 50\% & Data set 2, 50\%\\
  \includegraphics[width=9cm]{dataGeneration-Affy50} &
  \includegraphics[width=9cm]{dataGeneration-Illu50}\\
\end{tabular}

\end{document}
