The proper syntax would be
/ApplyMap('PercentMap_2005',State,0) as PercentOf2005GSP,
/ApplyMap('PercentMap_2006',State,0) as PercentOf2006GSP
Although, I think the data model would be better and you wouldn't have to maintain the script so much if you created one column with the value of year.
State Year CA 2005 CA 2006 NY 2005