Also as Cinisajoy alluded to in an earlier post life expectancy is the average of everyone in the population infants to elderly. Some infants will unfortunately die and some people will die at a younger age--lowering the average. So as we age, our life expectancy increases. As Tony stated, the average life expectancy in the U.S. (where I live) is 78.4 years. But, at age 55, my life expectancy is 85.5 years--calculated using the calculator provided by the US Socials Security Administration calculator.
https://www.ssa.gov/OACT/population/longevity.html
Just noticed that sjfan pretty much said the above in an earlier post :-)