Per

prep.
  1. Through; by means of; through the agency of; by; for; for each; as, per annum; per capita, by heads, or according to individuals; per curiam, by the court; per se, by itself, of itself. Per is also sometimes used with English words.
    2. Per annum ,
    by the year; in each successive year; annually.
    Per cent, Per centum, per cent ,
    by the hundred; in the hundred; a proportion multiplied by one hundred; -- used esp. of proportions of ingredients, rate or amount of interest, and the like; most commonly used in the shortened form per cent; as, 5 is ten per cent of 50. It is commonly symbolized with the per cent sign, "%".
    Per diem ,
    by the day.