translation.en: This is the number of distinct people that have helped us digitize at least one word out of a book through reCAPTCHA: 750 million, which is a little over 10 percent of the world's population, has helped us digitize human knowledge.
translation.zh: 这个数字是 通过reCAPTCHA帮助我们电子化书籍中单词的人数 7.5亿 多于世界总人口的十分之一的人们 帮助我们电子化人类的知识