According to https://theconversation.com/in-places-where-its-legal-how-ma... (as of 2019) between 0.3% and 4.6% of all deaths are assisted suicide or euthanasia in jurisdictions where it’s legal.

The paper they report on further notes:

pain is not the main motivation for PAS (physician-assisted suicide)… The dominant motives are loss of autonomy and dignity and being less able to enjoy life’s activities.