Luger vs thirty-eight

Luger

noun

  • A German semiautomatic pistol used by their troops in both World Wars. 

name

  • A surname from German. 

thirty-eight

num

  • The cardinal number immediately following thirty-seven and preceding thirty-nine. 

How often have the words Luger and thirty-eight occurred in a corpus of books? (source: Google Ngram Viewer )