NETWORKDAYS calculation for entire column

[Salient]

Hello and greetings etc.

Am sure you can do this but can't find anything on the web.

On my spreadsheet column D contains dates and column E contains date

I want to calculate the difference in days between column E and column D.

This works fine =NETWORKDAYS(E2,D2)

Now if I paste this through the existing rows the calculation is working for each row. So far so good.

However an issue with rise if an additional line is added to the spreadsheet



Is there a way to substitue a variable, for want of a better term, so the calculation isn't row specific, ie a new row and the formula will automatically calculate the difference? Or do I have to extend my paste to the next twenty or so rows to cover an expanded row count?