Share of people always wearing a helmet while biking in Finland 2018, by education

The question was phrased as follows: "Käytättekö kypärää pyöräillessänne?" The answer options were 1) always, 2) often, 3) sometimes, 4) not at all, 5) does not apply to me. Those choosing 5) does not apply to me were left out of the observations. After this, the observed figures are those who answered the question with 1) always. The source provides the following information: "Information is collected by a mail and online questionnaire.
The respondents are at least 20 years old and have permanent residency in Finland. There is no upper age limit.
The questionnaire is sent to people drawn by random sampling from the data of the Population Register Centre.
The questionnaire form is available in Finnish, Swedish, Russian and English. The survey is carried out annually at the national level (sample size 10,000). This allows processing the findings only on the national level, not by any smaller regions.
Once every four years, the sample size is expanded to enable following the changes by counties at a rough level (sample size 3,300/county)."