Google WMT Structured Data Counts Incorrect - Why Is That?

[webmuppet]

I've noticed that in WMT Google under reports the number of pages of structured data we have by quite a wide margin. Does anyone know what this might mean?

[aakk9999]

How are you counting your pages with structured data? Every single URL that has structured data?

Robots.txt exclusion will certainly impact Google's count as it is not allowed to access the page. I am not sure if noindex/canonical will also impact the count or not.