Hope someone can help here!

Code Year Jan Feb Mar Apr... ect

3/02 2004 190 189 191 191
3/02 2005 205 206 208 209
3/03 2004 178 178 181 182
3/03 2005 185 186 185 187

I need to look up a value by selecting a code ref ie 3/02, a year, and a month
My source data sheet has 1600 rows and is set up like this & I don't want to
change it! I have 10 years of data with over 60 different codes
I intend to ask a user to select code; year; month from drop down boxes and
present a single value eg code 3/02; year 2005; month Mar = 208