What does the Instanced Foliage Count mean?

Why are some Foliage counted as 10,0, and some as 0,2? What does it mean?

See image.

The first number is the foliage count in the CURRENT LEVEL, whereas the second larger number includes foliage in all sublevels.
Kindof annoying that I had to read the ■■■■■■■ source code to figure this out.