helter-skelter vs posthaste

helter-skelter

adv
  • In confused, disorderly haste. 

noun
  • A helical fairground slide. 

  • Confusion or turmoil. 

adj
  • Carelessly hurried and confused. 

posthaste

adv
  • quickly, as fast as someone travelling post; with great speed 

How often have the words helter-skelter and posthaste occurred in a corpus of books? (source: Google Ngram Viewer )