How to change the height of a (multi)row in tabular with math

Question

I have the following code:

\documentclass{article}
\usepackage{multirow}
\begin{document}
\begin{table}[htbp]
    \centering
        \begin{tabular}{lcccl}
  \textbf{Irland}       &    -   &   -    &     x    &   $ FE_{UN}(t) - FE_{UN}(t=2003)$     \\ \hline
  \textbf{Portugal} &   x  &   x &    x  &    \multirow{2}{*}{$ FE_{UN}(t) - \displaystyle{ \frac{1}{2}\cdot\sum_{u=t-2}^{t-1} FE_{UN}(u)}$}    \\ 
  \textbf{Spanien}  &           x  & x   &     x     &  \\ \hline
        \end{tabular}
\end{table}
\end{document}

which simply doesn't look good.

How can I fix this?!

Answer 1

the following

\documentclass{article}
\usepackage{multirow}
\usepackage{bigstrut}
\begin{document}
\begin{table}[htbp]
    \centering
        \begin{tabular}{lcccl}
  \textbf{Ireland}       &    -   &   -    &     x    &   $ FE_{UN}(t) - FE_{UN}(t=2003)$     \\ \hline
  \textbf{Portugal}\bigstrut &   x  &   x &    x  &    \multirow{2}[4]{*}{$ FE_{UN}(t) - \displaystyle{ \frac{1}{2}\cdot\sum_{u=t-2}^{t-1} FE_{UN}(u)}$}    \\ 
  \textbf{Spanien}\bigstrut  &           x  & x   &     x     &  \\ \hline
        \end{tabular}
\end{table}
\end{document}

gives