per capita

"per capita"という表現があります。経済用語と言ってもいいと思いますが、”一人当たり”という意味です。

多くは一国の経済などについて、国民一人当たりの収入（an income per capita）といったコンテクストで使われます。

"capita"とは、ラテン語の"caput"（頭）を語源としています。つまりは頭数でみた場合の話、というのが"per capita"の言いたいことであり、一国の経済に関する堅苦しい話以外でも、”一人当たりの”話をする場合には、"per capita"と言えばいいのです。


Europe has twice our per capita garlic consumption, and we hoped to take Europe by storm. But we're not doing well over there -- they just won't change, " he says, exasperated. The Europeans, it seems, prefer to buy whole garlic bulbs and peel by hand.
(Richard Wolkomir. Without garlic, life would be just plain tasteless. Smithonian. 1995.)


上の用法にも見られる通り、"per capita"は形容詞としても機能しています。


Even though just 20 percent of Americans smoke now, more than 40 percent of U.S. adults smoked in 1960 and the population is still paying the price, the report from the National Research Council found.

"Other factors, such as obesity, diet, exercise, and economic inequality, also have likely played a role in the current gap and divergence between the United States and other countries," the panel of experts appointed by the council wrote.

Many experts have tried to explain why the United States, which spends more per capita on healthcare than any other country and which has a relatively wealthy and well-nourished population, should rank so poorly against other countries in terms of lifespan.

Gerontologist Eileen Crimmins of the University of Southern California and colleagues looked at cause-of-death statistics for an explanation.

Smoking -- which kills directly and indirectly through secondhand smoke effects -- seemed to be a major factor, they found.
(Maggie Fox. Smoking explains why Americans don't live longer. Reuter. January 25, 2011.)


上記の記事では、米国の平均寿命が他先進国に比べて短い傾向にあるのが喫煙に関連しているというものですが、国民一人当たりの医療費は他国よりも上なのに、という皮肉な状況がリポートされています。

経済のコンテクストで用いられることが多い"per capita"ですが、要は頭数で割った結果、ということであり、”名古屋では市民一人当たりの喫茶店数が全国一”、だとか、”市民一人当たりの餃子消費量が一番多い”（宇都宮？浜松？）、ということでも何でもいいのではないかと思います。