I am little bit confusing how to calculate $δβ/δρ$ value if I have set of values like this.

I have the values of $β$ and $ρ$ like this.
$$ \begin{array}{l|l}
 β & ρ\\ \hline
 0,324 & 0,687\\
 0,322 & 0,695\\
 0,319 & 0,721\\
 0,317 & 0,759\\
 0,316 & 0,798
\end{array} $$
from the above set of values i need to calculate this "$δβ/δρ$" $=$ ?

Can anyone explain me how to calculate it in microsoft excel or normal method?