armed forces vs troopers

armed forces

noun
  • The military forces of a nation, such as the army, navy, air force, marines, and sometimes, coastguard or border guard, which are tasked with the defence of the nation and its citizens, if necessary through use of deadly force. 

troopers

How often have the words armed forces and troopers occurred in a corpus of books? (source: Google Ngram Viewer )