I'm ashamed we Bulgarians haven't done better marketing of it as it is really good and superior than Greek. Everyone knows about Greek yogurt but nobody knows about Bulgarian * . I love Greek yogurt too, but the reason it's so thick is that it is strained.
Bulgarian yogurt derives its thickness and structure from the fermentation process, and good yogurt should not fall off if you turn the jar upside down.
* - at least in USA, in east Asia (Japan, Thailand in my experience) the most popular brand of yogurt is named "Bulgaria" and is in every 7/11 or supermarket.
EDIT: format of the asteriks