I don't need to go read a book. I'm Spanish and this is my culture.

I lived with my parents while studying at the university. And when I got my first job at age 24 I moved out to my own place (rental).

This study accounts for this cultural preference. That is why it breaks down the statistics by age.

And when those between the ages of 30 and 34 are asked why they still live with their parents, "lack of own income is cited as being of high or very high importance by 66.3% of young Spaniards, 62.4% of Portuguese and 61.2% of Italians.".

You should read the report. It's very interesting.