Those scores are not objective. Don’t read it as “people are this happy” but as “people report in a survey they are this happy”. People will report high scores because they think they should (“My country always scores high on this, I don’t want to spoil it” ), because the previous scores change people perception (“Fins are famous for being happy, I can’t put less then 7, right?”) or because they want to defend their country (“Enemies want to see Israel suffer but I will show them we’re still happy here despite all of it: 10”). People will also put low scores to protests (“Nothing change in my life in the last year but I will put 1 to show that Trump sucks”).
Those scores are not objective. Don’t read it as “people are this happy” but as “people report in a survey they are this happy”. People will report high scores because they think they should (“My country always scores high on this, I don’t want to spoil it” ), because the previous scores change people perception (“Fins are famous for being happy, I can’t put less then 7, right?”) or because they want to defend their country (“Enemies want to see Israel suffer but I will show them we’re still happy here despite all of it: 10”). People will also put low scores to protests (“Nothing change in my life in the last year but I will put 1 to show that Trump sucks”).