Template:Title year2range-1/doc

Usage
Takes a year from the name of the page, subtracts 1, and converts it into a range, by applying Year2range to Title year. It does not pass through the Title year parameters but can take a parameter to specify the range, which is 1 year by default. So eg on :

To go the other way, to generate a year from a range in the page name, you just use Title year (or Title year+1 or Title year-1 as appropriate)