Use a script like the following:
{
tempregion = substr($3,1,7)
tempyear = substr($2,4)
if ( tempregion == "REGROLL" && tempyear >= 1996)
printf("%s %d %s %s %f %f\n", $1,tempyear,$3,$4,$5,$6)
}
$0 refers to the whole input string - use it only if you need to print the input as is, if you need modifications print individual fields (as shown above) instead.
I have assumed that the individual fields are separated by a whitespace. Please modify appropriately if it not so.
-amar