Le Creuset cookware

Does anyone know what year Le Creuset skillet/pans with the removable wooden handles stopped making the enamel colored bottoms, as the 2nd photo reflects, and switched to cast iron with the round circle in the center with the pan size inside? I have a number of old Le Creuset pans I've purchased over the years (all used) that are in great condition and I use every day but would like to understand their history a little better.