shackled vs tethered

shackled

adj
  • Restrained by shackles, chained. 

tethered

adj
  • tied, strapped, especially with tethers or hobbles. 

  • connected (especially a mobile phone to a computer, for use as a wireless modem) 

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