Republic of China does not have any legally designated official language, but Mandarin plays the role of the de facto official language. Around 70% of Taiwan's population belong to the Hoklo ethnic group and are speakers of Taiwanese Hokkien as native language. The Hakka group, comprising some 14–18 per cent of the population, speak Hakka. Although Mandarin is the language of instruction in schools and dominates television and radio, non-Mandarin Chinese varieties have undergone a revival in public life in Taiwan, particularly since restrictions on their use were lifted in the 1990s. Formosan languages are spoken primarily by the indigenous peoples of Taiwan. They do not belong to the Chinese or Sino-Tibetan language family, but to the Austronesian language family, and are written in Latin alphabet. Their use among aboriginal minority groups has been in decline as usage of Mandarin has risen. Of the 14 extant languages, five are considered moribund. Classical Chinese Since the May Fourth Movement, written vernacular Chinese had replaced Classical Chinese and emerged as the mainstream written Chinese in the Republic of China. But Classical Chinese continued to be widely used in the Government of the Republic of China. Most government documents in the Republic of China were written in Classical Chinese until reforms in the 1970s, in a reform movement spearheaded by President Yen Chia-kan to shift the written style to a more integrated vernacular Chinese and Classical Chinese style (文白合一行文). After 1 January 2005, the Executive Yuan also changed the long-standing official document writing habit from vertical writing style to horizontal writing style. Today, pure Classical Chinese is occasionally used in formal or ceremonial occasions, religious or cultural rites in Taiwan. The National Anthem of the Republic of China (), for example, is in Classical Chinese. Taoist texts are still preserved in Classical Chinese from the time they were composed. Buddhist texts, or sutras, are still preserved in Classical Chinese from the time they were composed or translated from Sanskrit sources. In practice there is a socially accepted continuum between vernacular Chinese and Classical Chinese. Most official government documents, legal, courts rulings and judiciary documents use a combined vernacular Chinese and Classical Chinese style (文白合一行文). For example, most official notices and formal letters are written with a number of stock Classical Chinese expressions (e.g. salutation, closing). Personal letters, on the other hand, are mostly written in vernacular, but with some Classical phrases, depending on