Set the cutoff year for determining the century for a date (used in conjunction with dateFormat 'y'). If a numeric string only ('0'-'99') is provided then this value is used directly. If a string value has a '+' then it is added to the current year. Once the cutoff year is calculated, any dates entered with a year value less than or equal to it are considered to be in the current century, while those greater than it are deemed to be in the previous century.
A string representing an cutoff year
+20: If the current year is 2015, years 00 to 35 are considered to be years 2000 to 2035. 36 to 99 are considered to be 1936 to 1999.