above-board vs sincere

above-board

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

adv
  • Honestly; openly. 

sincere

adj
  • Meant truly or earnestly. 

  • Genuine; meaning what one says or does; heartfelt. 

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