IUCN has developed a ranking system combining Human Wellbeing (HWI) and ecosystem wellbeing (EWI) into a single Wellbeing Index (WI). The method to arrive to these numbers is further explained in well being backgrouder.
from: IUCN – World Conservation Union document: Well Being of Nation Ranking in detail see also: IUCN – World Conservation Union XlnkS58D XlnkC189D