\begin{table}%t1 
  \caption{The distribution of stars over main-sequence spectral type for the Kroupa and Salpeter mass distributions (BD = brown dwarfs). \label{table:massfractions}} 
  \small%\centering
$$
  \begin{tabular}{l r@{$-$}l r@{.}l r@{.}l r@{.}l r@{.}l}
    \hline
    \hline
    SpT                             & 
    \multicolumn{2}{c}{Mass range}  &
    \multicolumn{4}{c}{Kroupa}      & 
    \multicolumn{4}{c}{Salpeter}    \\
    %\hline
                                    & 
    \multicolumn{2}{c}{$({M}_\odot)$}  & 
    \multicolumn{2}{c}{${\mathcal F}_N$ (\%)}           & 
    \multicolumn{2}{c}{${\mathcal F}_{M}$ (\%)}           & 
    \multicolumn{2}{c}{${\mathcal F}_N$ (\%)}           & 
    \multicolumn{2}{c}{${\mathcal F}_{M}$ (\%)}           \\
    \hline
    B            & 3.0 & 20    &   1&45  &  24&76   &    0&10  &   8&66 \\
    A            & 1.5 & 3.0   &   2&28  &  13&05   &    0&18  &   5&31 \\
    F            & 1.0 & 1.5   &   2&72  &   9&15   &    0&22  &   3&86 \\
    G            & 0.8 & 1.0   &   2&22  &   5&52   &    0&18  &   2&30 \\
    K            & 0.5 & 0.8   &   7&45  &  12&92   &    0&61  &   5&45 \\
    M            & 0.08& 0.5   &  51&48  &  30&28   &   14&09  &  32&07 \\
    BD           & 0.02& 0.08  &  32&41  &   4&33   &   84&61  &  42&34 \\
   % \hline
    All          & 0.02& 20    & 100&00  & 100&00   & 100&00   & 100&00 \\
    \hline 
  \end{tabular}$$ 
\end{table}