GENEVA, March 29 (Xinhua) -- Multilingual Switzerland is dominated by German-speakers, but the percentage of French speakers rose from 18 to 23 percent between 1970 and 2016, the Swiss Federal Statistical Office said Thursday in a report.

The office released statistics showing that the linguistic landscape in Switzerland has changed over the past 40 years, finding that three of the four official languages have declined whilst French-speakers have grown overall.

The proportion of people who did not speak a Swiss national language as their first language increased significantly: from 4 percent in 1970 to 22 percent in 2016 said the statistical office.

The report found that German (and Swiss German), Italian and Romansh have declined, while French and non-national languages have gained momentum since the 1970s.

The proportion of people who speak Swiss German as their main language fell from 66 percent to 63 percent between 1970 and 2016, according to the Federal Statistical Office figures.

The number of Italian speakers from 11 to 8 percent and Romansh speakers also fell, from 0.8 percent to 0.5 percent respectively.

The statistical office said this increase was related to a change in the questionnaire which made it possible for people to name several main languages since 2010.

English and Portuguese were the two foreign languages mentioned the most.

Swiss German was the most frequently spoken language at work (65 percent), followed by German (35 percent) and French (29 percent). Some 19 percent of people spoke English at work and 9 percent spoke Italian.

At home or when talking to relatives, people usually spoke Swiss German (59 percent) or French (24 percent). Other languages spoken in a family setting were German (11 percent) and Italian (8 percent). English (5 percent) and Portuguese (4 percent) were once again the most frequent foreign languages cited in this context too.

One in five people in Switzerland over the age of 25 was studying a foreign language as an adult, said the report.

English was chosen most frequently, by 35 percent of adult learners across all linguistic areas of the country.

It was a far more popular choice than French (15 percent), German (13 percent) and Italian (11 percent).