An educational calculated column–academic year

I work in an educational institute. In most of our lists the users need a column where they can enter the academical year. This is always in a default format. For example: 2011-2012. We could create a site column with all those values but I prefer to use a calculated column. This is the formula I created:




This formula calculates the academic year for a given datetime column. In our country the new academic year starts at the 9th of september.