\def\onecol{red}
\def\twocol{green}
\def\threecol{lightblue}

\renewcommand{\tdx}{0.5} % depth of 3d
\renewcommand{\tdy}{4}
%------------------------------------------------------------------
    %this is the way to redefine styles
    % \newpsstyle{mytickstyle}{linewidth=1pt,linecolor=blue}
    %
    \newpsstyle{diagframestyle}{linewidth=1pt,linecolor=black,fillcolor=white}
    \bardiagrambegin{13}{100}{3cm}{2}{7}{1cm}{0.1cm}
       \baritem{1990}{72}{\onecol}
        \subbaritem{2000}{50}{\twocol}
        \subbaritem{2010}{63}{\threecol}
       \baritem{1990}{81}{\onecol}
         \subbaritem{2000}{99}{\twocol} 
         \subbaritem{2010}{50}{\threecol}  
%        \baritemCYL{1990}{41}{\onecol}
%         \subbaritemTD{2000}{30}{\twocol}
%         \subbaritemTD{2010}{21}{\threecol}
    %\drawlevellines 
    \bardiagramend
      {\parbox{14cm}{\vspace{-1.5cm}\hspace{-0.7cm}
          \begin{tabular}{p{7cm}p{6cm}}
            \centering Alpha's & \centering Beta's 
          \end{tabular}
          \\[0.6cm]
          \centering \large Year}}
      {\large Graduated (\%)}
.
