People are sicker for longer before they die. Their Marginal Decade is spent largely as a patient. When centenarians die, in contrast, they have generally (though not always) been sick and/or disabled for a much shorter period of time than people who die two or three decades earlier. This is called compression of morbidity, and it basically means shrinking or shortening the period of decline at the end of life and lengthening the period of healthy life, or healthspan.
