Trends by sex
There has been a long and continuing decline in death rates in Australia. Over the period 1907 to 2019, the age-standardised death rate for males fell by 72% and by 76% for females.
Death rates have historically been higher for males than for females; however, the gap is closing over time. The difference between male and female age-standardised death rates was largest in 1968, when the rate difference was 642 deaths per 100,000 population. In 2019, the rate difference between males and females was 186 deaths per 100,000 population.
The reduction in rate difference between male and female rates since 1968 has largely been driven by the reduction in deaths due to circulatory diseases. This was influenced by several factors, including improvements in surgical techniques, hospital care, diagnosis and pharmaceuticals, as well as modifications to lifestyle factors such as smoking, diet and high blood pressure. See more on Mortality inequalities in Australia.

Source: AIHW National Mortality Database (Table S4.1).
Trends by cause of death
The decline in deaths in the first half of the last century was associated with factors such as control of infectious disease and better hygiene and nutrition. The decline in the later years was associated with improvements in road safety measures, falls in smoking rates, and improvements in prevention, detection and treatment of disease such as cardiovascular disease and other chronic diseases. See more on Mortality over the twentieth century in Australia.
Circulatory diseases have consistently been a leading cause of death for Australians over the last century, but death rates have been steadily declining. Deaths from circulatory diseases peaked in 1968 at 830 deaths per 100,000 population (age-standardised rate), and have since dropped to 128 deaths per 100,000 population in 2019. Cancer (all neoplasm) deaths, after adjusting for differences in age structure, peaked in 1985 (217 deaths per 100,000 population) and have gently declined to 158 deaths per 100,000 population in 2019.
Age-standardised rates of deaths due to respiratory diseases and injury and poisoning declined over the last century.

Source: AIHW National Mortality Database (Table S4.2).