. 2018 May 8;15(5):938. doi: 10.3390/ijerph15050938

Table 1.

Indicators of the old-age structure.

Indicators	Definition	Rationale	References
Centenarian ratio	Number of centenarians per 100,000 people	To reflect the extreme regional longevity rate	Song et al., 2016, [5]
Longevity index	The proportion of 90⁺/65⁺ population	To reflect the extreme longevity among the elderly population	Lv et al., 2011, Song et al., 2016, Magnolfi et al., 2007, [2,5,9]
Longevity level	The proportion of 80⁺/60⁺ population	To reflect the secondary longevity rate of the elderly population	Li et al., 2013, [26]
Aging tendency (60⁺ ratio)	60⁺ elderly population/total population	To reflect the total local elderly population proportion and aging tendency	Wang et al., 2015, [11]
80⁺ ratio	80⁺ elderly population/total population	To reflect the proportion of the second oldest group in the total population	Wang et al., 2016, [6]
90⁺ ratio	90⁺ elderly population/total population	To reflect the proportion of extreme elderly in the total population	Lv et al., 2011, [2]
95⁺ ratio	95⁺ elderly population/total population	To reflect the proportion of extreme elderly in the total population