Above average the life expectancy of your country, for starters.

Although, that number is a bit misleading because the average life expectancy does not control for individual health (obviously, it's an average, it's not suppose to). How many additional years could be added to the average life expectancy in presence of modern medicine, and absent of self inflicted disease? I'd say easily the average for most developed countries would boost up 3-4 years at least.

And perhaps defining "healthy" is also important, because it is also relative.