downward vs straight ahead

downward

adv
  • Southward. 

  • At a lower level. 

  • Toward a lower level, whether in physical space, in a hierarchy, or in amount or value. 

adj
  • Located at a lower level. 

  • Moving, sloping or oriented downward. 

straight ahead

adv
  • directly ahead, without deviation 

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