Do the healthy years take mental health and quality of life into account or just the total number of days you are not sick (and still a cold or pneunomia is quite different). I ask this because Japan is reputedly a country of hard wokers and possibly have the highest level of "karoushi" (overwork death).
I understand that Japanese people are less often sick than, let's say Nothern Europeans, because the climate is much milder and people try hard to prevent virus spreading, eg. by wearing a mask when they are ill. I am amazed that we still have 21 degree in Tokyo in November. Last week, we had 26 degrees with blue sky every odd day (and cold rainy days the other ones). Basically, Japanese autumn is very much like English summer and warmer than the Norwegian and Finnish one.