As stated on the pages, for the Overall Academic Performance Rating or State Overall Score, score of 100 is the highest while 60 is the lowest. The higher the score, the better. So score of 100 is the best. Be aware that the score has a floor value of 60.

If the school's state overall score is 90, it means top 10/(100-60)*100=25% or 10%*2.5=25% in the state. In this instance, it can be considered as state overall percentage.

Note that the state overall measures English and Maths test results only while year 12 results and school ranking is based on the results of all subjects. For school ratings, the more books, the better literacy test results; the more medals, the better the numeracy test results. See also How "stars" and scores are accurately tabulated.

Related: National Overall Score is measured in similar way.