I need to get skilled and unskilled wages data from 1998-2011 from ASI data for indian manufacturing.The data given on ASI website gives data for different years using NIC-98,NIC-04 and NIC-08 classification? How to get the data at 3-digit classification for the period 1998-2011 using NIC-08 classification? how to construct the concordance table at 3-digit level b/w NIC-08,NIC-04 and NIC-98?