english: Spending per student only explains about, well, less than 20 percent of the performance variation among countries, and Luxembourg, for example, the most expensive system, doesn't do particularly well.
non_english: Ukupna potrošnja  po studentu objašnjava, pa, manje od 20 posto varijacije u uspehu  kod različitih zemalja, Luksemburg, na primer, najskuplji sistem ne postiže posebno dobre rezultate.