Simple Forecast

[#1]

hi everyone:)

I need your help.

I like to have a chart with a simple forecast. In my chart is the remaining lifetime of a material.

for example:

a material XXX with a remaining lifetime of 50 month on feb-2015

and I like to have a line chart who starts on 50 on feb-2015 than 49 on mar-2015 than 48 on apr-2015...reduce each month -1.

maybe someone of you have a solution:) thanks to all.