Calculate Percentage of Items Sold based on Cell Values and No. Of Rows

Hello, I am trying to calculate the % of unsold items on my spreadsheet.

https://docs.google.com/spreadsheets...it?usp=sharing

On my Furniture sheet, each row represents a single item. I have 8 items in total.

Items that have not yet been sold have a blank 'Resell' value, and these have been marked in green:

example.png

Therefore, 5/8 items have not yet been sold (62.5%). I would like to represent this value as a percentage on my Totals sheet.

The sheet should also allow for new items (rows) to be added to the Furniture sheet, so basically all rows from A2 downwards if populated should add to the row total and subsequent calculation.

I hope that's clear and thanks again in advance for any help.

That's great Kaper appreciate the speedy response.