year-on-year 復習

　中国の、９月の北朝鮮からの輸入額は約38％と大幅に減少し、これで７か月連続減となります。最近の北朝鮮によるミサイル発射に対する貿易制裁が原因であると考えられます。
China Sept. imports from N. Korea dip

BEIJING (Reuters) — China’s imports from North Korea fell for a seventh straight month in September, dropping 37.9 percent year-on-year as Beijing implemented the latest U.N. trade sanctions aimed at persuading Pyongyang to rein in its nuclear and missile programs.

The sanctions, which could cut off one-third of North Korea’s total annual exports of $3 billion, took effect in September, but China enforced the new measures from Aug. 15.

China-U.S. ties have been strained by U.S. President Donald Trump’s criticism of China’s trade practices and by demands that Beijing do more to put pressure on North Korea.

The sharp decline in imports in September compares to a 1 percent drop in August.

Data released by China’s General Administration of Customs showed China had a $1.07 billion trade surplus with North Korea in the first nine months of this year.

http://the-japan-news.com/news/article/0004002888

　取り上げる表現は"year-on-year"です。『ジーニアス英和辞典』第４版（大修館）で調べてみると、「（数字、物価などが）年度ごとの、前年比の」とありました。例文としては、"a 3% year-on-year increase"で「前年比３％の増加」となります。因みに、ハイフンを除いた"year on year"は、「前年に比べて、年々、毎年」という意味があります。LDOCEでは、"compared with the previous year"と定義されています。(Akim)