importune vs sifflicate

importune

verb
  • To bother, irritate, trouble. 

  • To harass with persistent requests. 

  • To approach to offer one's services as a prostitute, or otherwise make improper proposals. 

sifflicate

verb
  • To criticise 

  • To suggest 

  • To supplicate, petition, importune, or wheedle 

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