\begin{Schunk}
\begin{Sinput}
 t1 <- with(dat, table(gunlaw, owngun, exclude=NULL) )
 t1.prop <- prop.table(t1, margin=2)
 t1.prop
\end{Sinput}
\begin{Soutput}
        owngun
gunlaw          YES         NO    REFUSED       <NA>
  FAVOR  0.69879518 0.83014537 0.56666667 0.00079713
  OPPOSE 0.28915663 0.14766641 0.33333333 0.00000000
  <NA>   0.01204819 0.02218822 0.10000000 0.99920287
\end{Soutput}
\end{Schunk}
