Hello,
In 8.2 and later you can make date-based parameters, which would simplify things.
Otherwise, you can create a date value using a calculated expression like this:
DateFromMDY(1, 1, 'Parameter 1'p)
This will create values like '01 January 2018', but you can set the format of this data item to show the year only.
Let us know if this helps!
Thanks,
Sam