More importantly, do you factor in people died from otherwise treatable diseases as negative happiness, or neutral (as they no more have a brain to secrete serotonin)? Is death unhappiness? For the subject and his relatives? When death is commonplace is it still a source of unhappiness or accepted as a part of natural flow, with human life being regarded as less permanent and more ephemeral, with greater emphasis on the present moment and less on future plans and ambitions?

Death is commonplace everywhere. Everybody dies.