Best way to distinguish extremes in a bubble without value label

I'm displaying some data related to categories using a series of overlapping bubbles.

1. Bubble sizes correspond to category data value so one can compare categories between each other based on bubble size.
2. Within bubbles a smaller bubble displays category related data according to bubble size. The more relevant the data, the larger the inner bubble.
3. When inner bubble exceeds outer bubble size it shows as an outline to the original bubble but its size is capped to 110%.
4. Categories are displayed next to the corresponding bubble and that's the only information I have on the bubble series.

The problem

Bubbles don't display any quantitative information so there's no way to distinguish between 0% (no inner bubble) and 100% (inner bubble of the same size than outer one).

I was thinking to always display inner bubble of 2% size which would partially solve the 0% problem, but wouldn't solve the 100% one.

I was wondering what would be a better way to display this data using bubbles without any problem extreme values?

Following image is just a partial example of bubble display.