Which Greek root is related to the study of population statistics?

Which Greek root is related to a widespread occurrence of a disease in a community?

Which Greek root is related to a disease that is constantly present in a particular area?

What is the meaning of the Greek root 'cracy'?

Which Greek root is related to a system of government by the whole population or all the eligible members of a state?

Which Greek root is related to the study of population characteristics?

Which Greek root is related to a disease that is prevalent worldwide?

Which Greek root is related to a disease that is prevalent in a particular species?

What does the Greek root 'demo' stand for?