Google Webmaster Tools recently added support for domain properties as opposed to the default URL prefix properties. However, they have not yet updated their sitemaps API to support domain properties.
This means that in order to see the most detail available for your sites index you need to add it as a URL prefix property, as shown in the image below:
It is possible to add both - you may have your existing Domain property and still add a new URL prefix for your sites main address. Once you do this the information will become available on Index Ninja within 2-24 hours.