收入不均衡一直是今年的热门讨论话题，无论是托马斯•皮凯蒂在其畅销书《21世纪的资本》（Capital in the Twenty-First Century）中对这一问题的剖析，还是美国总统奥巴马提高最低工资标准的行动，我们都能看到它的身影。

    人们所关心的核心问题是：收入不均衡是否会拖累美国经济？

    标普评级（Standard & Poor’s Ratings Services）发布的一篇新报告对此予以了肯定的回答。

    研究人员写道，“在当前，美国这个世界最大的经济体正挣扎着走出大萧条阴影，而政府又急需资金为人口的老龄化买单，因此，美国目前的收入不均衡水平正在抑制GDP的增长。”

    相关数据并不一定是最新的，但是一系列图表却简单明了地总结了这一趋势背后的推手，以及可能对经济增长造成的影响。

    美国个人收入正呈现出集中化趋势。当我们使用基尼系数来衡量时，这一趋势尤为明显。该系数是用来衡量收入分配的指标，因此也能衡量收入的不均衡性。基尼系数越高，最高收入和最低收入的差距也就越大，而这正是我们在过去数十年中所看到的趋势。

    Income inequality has been the topic of vigorous debate this year from Thomas Piketty’s breakdown of the issue in his best-selling book, “Capital in the Twenty-First Century,” to President Obama’s campaign for a higher minimum wage.

    Everyone has a central question: Is income inequality holding back the U.S. economy?

    A new report by Standard & Poor’s Ratings Services says yes.

    “The current level of income inequality in the U.S. is dampening GDP growth,” the researchers wrote, “at a time when the world’s biggest economy is struggling to recover from the Great Recession and the government is in need of funds to support an aging population.”

    The data isn’t necessarily new, but the series of charts makes salient and concise arguments as to what’s been driving the trend and the impact it could be having on economic growth.

    U.S. incomes are becoming more concentrated. This is typically shown using a Gini coefficient, a measure of income distribution and thus income inequality. A higher number means the gap between top and bottom earners is getting further apart, which is the trend we’re seeing over the last several decades.