If you find the winter months tough, particularly during Decemberand January you may suffer from Seasonal Affective Disorder, which causes a low mood caused by the lack of light during winter.
It has seen bigger percentage drops only twice in the past ten years, in May 2010 andDecember 2003.
在过去十年中，只有两次跌幅百分比更大，分别是在2010年5月和2003年12月。
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Significantly, Japan overtook China as the biggest foreign holder of US Treasuries in December, and its monthly purchases have been consistently rising since May.