I want to know how many Stack Exchange sites there are.
Querying http://api.stackexchange.com/2.2/sites, using a filter that makes total appear, I find that the value is always zero.

For example,
          http://api.stackexchange.com/2.2/sites?filter=!6P-i5S514Gfnl

Responds:

{ "total": 0 }

Is that the intended behavior?