Evaluate the change in mortality over the course of the twentieth century.

Mortality decreased rapidly in young people from developed countries

Explanation:

During the 20th century, mortality has decreased in developed countries at quite constant rates (approximately 1-2 %). This decrease in mortality was primarily due to more efficient public health measures and medical research innovations which enhanced people's ability to fight against diseases. Nonetheless, this decline was lower in sub-developed countries, where structural problems affected (and indeed continue affecting) the life expectancy of people in these countries. In developed countries, it is also important to note that the important decrease in mortality during the 20th century has been especially concentrated at younger ages, thereby increasing this value in aged people.