JDK7 b55

charsets.jar: 6239629 (un-compressed)
EUC_TW.class 2313
EUC_TW$Decoder.class 298066
EUC_TW$Encoder.class 486890

EUC_TW has total of 55446 codepoints, including supplementary characters in u+20000-u+30000 area. The existing data structure (stored the supplementary character in surrogate form) and implementation obviously takes too much space.