expression
per mill; per mille; per mil
A unit meaning one-thousandth, used in statistics, finance, and science. Equivalent to 0.1%.
出生率は12パーミルだった。
The birth rate was 12 per mill.
この合金の不純物は2パーミル以下です。
Impurities in this alloy are below 2 per mille.
Borrowed from English 'per mill' or French 'pour mille', meaning 'per thousand'.