Passage: While other committees oversaw the tasks of promulgating Mandarin Chinese as the national language and creating simplified Chinese characters, Zhou's committee was charged with developing a romanization to represent the pronunciation of Chinese characters. Zhou said the task took about three years, and was a full-time job. Pinyin was made the official romanization in 1958, although (as now) it was only a pronunciation guide, not a substitute writing system. Zhou based Pinyin on several preexisting systems: the phonemes were inspired by Gwoyeu Romatzyh of 1928 and Latinxua Sin Wenz of 1931, while the diacritic markings representing tones were inspired by zhuyin.In April 1979, the International Organization for Standardization (ISO) in Warsaw held a technology conference. Speaking on behalf of the People's Republic of China, Zhou proposed the use of the "Hanyu Pinyin System" as the international standard for the spelling of Chinese. Following a vote in 1982 the scheme became ISO 7098.

Question: How long did the task take?
three years