Setting up incremental numbering in a text box

Hi all. First time posting on here.

I'm working with a document that will have incremental numbering on every page. For example see below

This will increase by 0.1% for every page. So 12.1%, 12.2%, 12.3%, etc....

I know there's a way to import a spreadsheet through data merge, but to save me typing out a spreadsheet, or manually typing out the increase on every page, is there a way of entering my own increments so that Indesign automatically fills in the blanks.

The above screenshot is part of a layout on the master pages so I want to avoid changing each page manually if I can help it. If not I'll just have to bite the bullet and type them out.

Any help would be awesome. Thanks