收入的改变，工作的改变和家庭费用的改变反映了这种周期性变化，而其它指标，如作为可支配收入部分的个人存款，数十年来已经逐渐减少了。
Changes in incomes, jobs and home prices reflect this cyclical behavior, while other indicators, like personal savings as a percentage of disposable income, have shown a gradual decline over decades.
而能源消耗——这通常是反映资源需求的一个指标性数据。
Consumption of energy-a good proxy for resources in general.
作为一项反映材料优劣的重要的评价指标，天然耐久性直接决定了材料的使用寿命。
As an important evaluating index reflecting the quality of materials, natural durability can directly determine the using longevity of materials.
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