Format issues in the data table of a chart

[Karenola]

I have a chart (showing the data table) that is linked to another spreadsheet. When that linked spreadsheet is open, the numbers in the data table show as percents, which is what I want. But when that linked spreadsheet is closed, the numbers in the data table become decimals, losing the percentage format. Do you know why that happens and how I can fix it? Thank you
Whoops. I meant to add that I have posted this at Experts-Exchange. I got one reply but it is not what I need.