Yeaaahh, I would love to find out as well. XD

See below.

I'm pretty sure it's just ten block symbols that are colored using coding.
██████████
I used alt+219 for the blocks and coding from here: http://www.furaffinity.net/journal/441426/

You could also type up the coding in a text document for 10%, 20%, etc. and then you need only to copy paste. Also, I do believe nesting coding doesn't always work, so you might not get what you expect. You can practice in the linked journal, but admins don't like when you abuse the color thing(mainly with those text picture things).

thanks, I'll try it in my html editor.