NJ Unrecovered Contributions, Need Help

This is for an IRA I have not contributed to since 2013.  I take the full RMD every year. The 1099-R lists the State Tax Withheld but State Distribution is blank.  Should I put the same amount NJ Withheld in the Distribution spot?  OR should I put the same amount as Gross Distribution?  I have no idea what they mean, what they are looking for, or how to calculate it.  Please advise.