How do you give a rank to a data range

I am looking at the ranking of universities in various rankings tables, and making an aggregation of this data.

The issue comes in that in some of the rankings, below a certain rank, the data is grouped. For example, after a rank of 9, the next 5 universities are just listed with a rank of 10-14, then the following 5 as 15-19.

What I need to be able to do, is to assign an exact value to those above which have a range. i.e. for those with a range of 10-14, can I assign them all a value of 10, or 12, for example, or what I am looking for, is if there is a statistical way to assign such a value?