You need the INDIRECT() function, which creates dynamic addresses.
Assuming that you have your year number in a separate cell (Say K1),
and that all your worksheets have the same format, i.e. "YEARNO(space)
information", you will need the following for your VLOOKUP():
VLOOKUP(A4, INDIRECT("'" & K1 & " information'!$A$4:$L$97"), 12, FALSE)

HTH
Kostis Vezerides