Hi,
I have 2 columns which process days it takes to finalise projects. The 1st
column display the days and the 2nd column display how many projects were
done within this day number:

Days Projects
4 5
12 2 etc.
(400+ projects per month)

Every month the detail is added to the list.

I need to calculate how many days were used for 80% of projects per month.

I use a pivot table to display the list and projects and then do a
calculation next to the pivot table, but this is very time-consuming.
Can you please help me with a function do to this?
Thanks
--
Hennie