Wordnet 3.0
ADVERB (1)
1. 
 by the year; 
 every year (usually with reference to a sum of money paid or received); 
- Example: "he earned $100,000 per annum"- Example: "we issue six volumes per annum"[syn: per annum, p.a., per year, each year, annually]
WordNet (r) 3.0 (2006):
per year
    adv 1: by the year; every year (usually with reference to a sum
           of money paid or received); "he earned $100,000 per
           annum"; "we issue six volumes per annum" [syn: per
           annum, p.a., per year, each year, annually]