In every language, a word's frequency is inversely proportional to its rank

Linguist George Kingsley Zipf found that a language's most common word appears roughly twice as often as the second most common, three times as often as the third, and so on. This pattern, called Zipf's law, holds astonishingly well across English, Chinese, and dozens of unrelated languages, and even shows up in city populations and web traffic.

— George Kingsley Zipf, Human Behavior and the Principle of Least Effort — Addison-Wesley, 1949