Why have improvements in mortality slowed down?

Why have improvements in mortality slowed down? Until recently, mortality rates in England and Wales had been falling steadily. However, since 2011, the rate of improvement has slowed and trends in mortality have become more erratic (Figure 1). Strikingly, a sharp rise in mortality in 2015 meant that life expectancy at birth actually fell, before it recovered in 2016. What is causing these changes in the long-term trend? The King's Fund