too much blank space

Question

How can I have less blank space on the top ?

\documentclass{beamer}
\mode<presentation>
{
  \usetheme{default}      % or try Darmstadt, Madrid, Warsaw, ...
  \usecolortheme{default}
  \usepackage{beamerthemesplit}% or try albatross, beaver, crane, ...
  \usefonttheme{default}  % or try serif, structurebold, ...
  \setbeamertemplate{navigation symbols}{}
  \setbeamertemplate{caption}[numbered]
} 
\usepackage{subfig}
\usepackage[lmargin=3.81cm,tmargin=2.54cm,rmargin=2.54cm,bmargin=2.52cm]{geometry}

\usepackage[utf8x]{inputenc}
\usepackage{amsmath}
    \begin{frame}{Aspects financiers}

    \begin{figure}[h]
        \begin{minipage}[c]{.46\linewidth}
            \centering
            \includegraphics[width=5.5 cm]{Frequence.PNG}
            \caption{Fréquence apparation réelle / estimation}
        \end{minipage}
        \hfill%
        \begin{minipage}[c]{.46\linewidth}
            \centering
            \includegraphics[width=5.5 cm]{gausienne.PNG}
            \caption{Courbe de Gauss}
        \end{minipage}
    \end{figure}
    Espérance : 100
    Ecart type : 7.7

    \end{frame}