WASHINGTON - More than one in five American residents now speaks a language other than English at home, according to a new research based on 2016 US Census Bureau data.

The research, conducted by the Center for Immigration Studies, shows that a record 65.5 million United States residents aged 5 years and older don't speak English at home, representing the largest percentage rise since 2010 among languages with more than 400,000 speakers for Arabic, Hindi, Urdu, Chinese, Persian, Haitian, and Gujarati.

Among them, 26.1 million (39.8 percent) told the US Census Bureau that they speak English less than very well. This figure is based entirely on the subjective opinion of the respondents.

In an objective test of English literacy, prior CIS research showed that even among immigrants who have lived in the country for more than 15 years, 43 percent score at the "below basic" level, which is sometimes equated to functional illiteracy.

Moreover, many Americans who speak a foreign language at home are not immigrants. The data show that half of the growth in foreign language speakers since 2010 is among those born in the US.

Overall, 44 percent (29 million) of those who speak a language other than English at home are US-born.

"The English language has always been part of the glue that holds our country together," said Steven Camarota, co-author of the report and Director of Research at the Center.

"But the number of immigrants allowed into the country is now so large that it may be overwhelming the assimilation process, including learning English."

CIS has also estimated in prior research that roughly one out of three immigrants who are naturalized US citizens has below basic English literacy.

Hindi is a national language of India, Urdu is the national language of Pakistan, Persian is the national language of Iran and Gujarati is spoken in India.

Xinhua