Shaded area representing uncertainty bars on a graph

[alis88]

Dear all

Please see the attached spreadsheet.

I was wondering how to automatically produce uncertainty lines on a graph, with the area in between them shaded (I have described what I mean using drawing tools).

In this example, the correct value is 50 +/- 1 so could be either 49, 50 or 51. This area must be shaded.

How can I do this? Do I need to use an area chart?

Thanks

Alis