The problem w/ efficiency measures generally is that there's progress to some theoretical maximum, and it comes with diminishing returns.
Breaking down life expectancy gains by demographics, the've moved more for men than women (since 1920, far more the reverse before), largely due to workplace risk, violence, and military service), and the poor/minorities rather than wealthy/majority (access, preventive care, environment, violence, stress).
The upper bound's moved little. Exceptional longevity is profoundly correlated geographically with poor recordkeeping.
See:
The difference in gains by age, here for England and Wales beginning 1700, through2013, w/ all ages from 1850: https://ourworldindata.org/uploads/2013/05/Life-expectancy-b...
Note that whilst at-birth increases (1850) from about 40 to 80, a 40 year old gains only 67 - 82 or so (15 years). It's early-life mortality that's changed most.
Similar US trends: https://lh5.googleusercontent.com/qtYQp1x-ZF9iXc-zVh7Kg2xJBX...
By gender/race, 1970-2010, US: https://www.cdc.gov/nchs/images/databriefs/101-150/db125_fig...
An unusual presentation, showing mortality by age in 1950 vs. 2015. Note the double factor: reduced infant/early childhood mortality, and somewhat reduced adult mortality: https://siepr.stanford.edu/sites/default/files/styles/page-w...
Discussion: http://conversableeconomist.blogspot.com/2018/04/inequality-...
Geographic distribution: https://localtvwtkr.files.wordpress.com/2017/05/s078658261-3...
There are also hidden costs: mortality is selective pressure, and we've lifted much of that for about 5 generations. I have concerns. (I'll also note this generally impacts the wealthy more than poor, within and between countries.)
