ground pounder vs ranker

ground pounder

noun
  • A military soldier whose primary role is infantry or the use of ground-based materiel. 

ranker

noun
  • A common soldier. 

  • One who ranks things, or arranges them in ranks. 

  • A kind of soil developed over non-calcareous material, usually rock. 

  • One with a specified rank. 

How often have the words ground pounder and ranker occurred in a corpus of books? (source: Google Ngram Viewer )