Dally vs yam yam

Dally

noun

  • A New Zealand person of Croatian or other Balkan descent. 

name

  • A surname. 

yam yam

noun

  • A person who speaks the Black Country dialect. 

  • Heroin. 

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