It's stated in the passage that.......

Life expectancy figures represent the average number of years people are expected to live. Over the years, life expectancy has improved steadily largely due to a decline in deaths during childhood. The development of drugs to combat infectious diseases, plus improved nutrition and better environmental sanitation have played major roles in combating early deaths. But significant differences in life expectancy remain, depending on people's race and sex, with higher rates for females than males.