above-board vs only too

above-board

adv
  • Honestly; openly. 

adj
  • In open sight; without trick, concealment, or deception. 

only too

adv
  • very, all too. 

  • to a high degree; very well or very much 

How often have the words above-board and only too occurred in a corpus of books? (source: Google Ngram Viewer )