per annum       
adverb  formal uk/pɜːr ˈæn.əm/ us/pɝː ˈæn.əm/ (written abbreviation p.a.)
 每年
used in business when referring to an amount that is produced, sold, or spent each year
  The country exports goods worth $600 million per annum. 该国每年出口价值6亿美元的商品。 
 Synonyms: annuallyyearly