Adult life expectancy is a little more interesting than life expectancy at birth as a measure of modern medical progress towards healthy life extension. Much of the innovation now is in ways to treat age-related conditions rather than in ways to reduce childhood mortality and control the more obvious infectious diseases. Removing childhood from the picture when considering the data narrows the focus to the effectiveness of medical technologies deployed in later life.
Here is a recent study that measures gains obtained in the past couple of decades, none of which is really due to any attempt to deliberately extend human life or tackle aging. Progress here stems from the deployment of incrementally better medical technology across the board. Once the research community begins to address aging in earnest, I'd expect the pace of growth in life expectancy to accelerate considerably - especially if the better path of SENS, rejuvenation, and repair of cellular damage is chosen over efforts to slow aging via metabolic manipulation.
Thanks to medical advances, better treatments and new drugs not available a generation ago, the average American born today can expect to live 3.8 years longer than a person born two decades ago. Despite all these new technologies, however, is our increased life expectancy actually adding active and healthy years to our lives? That question has remained largely unanswered - until now. In a first-of-its-kind study, [researchers] have found that the average 25-year-old American today can look forward to 2.4 more years of a healthy life than 20 years ago while a 65-year-old today has gained 1.7 years.
Synthesizing data from multiple government-sponsored health surveys conducted over the last 21 years [researchers] were able, for the first time, to measure how the quality-adjusted life expectancy (QALE) of all Americans has changed over time. The data shows that Americans are living longer, reporting fewer symptoms of disease, have more energy and show fewer impairment in everyday tasks such as walking than a generation ago. According to the study authors, a 25-year-old person today can expect to live 6 percent or 2.4 quality years longer than their 1987 counterpart.
Bear in mind that life expectancy is effectively a measure of what would happen if all change and progress was frozen where it is today. It measures past progress, not future outcomes. We are in the midst of a revolutionary period of change and acceleration in biotechnology and medicine, comparatively little of which has yet percolated into available medical technologies. So adjust your expectations for the future accordingly.