Values continue to trend upward in Volume 4, which covers countries of the world J-O. 10,000 value changes were recorded in British Commonwealth countries, while 24,000 changes were spread among non-British countries. New Zealand, Malaya and Mauritius are several of the British Commonwealth countries where particularly high numbers of value changes have been recorded. Value changes for non-British-area stamps are spread across a large number of countries. Among the most noteworthy is Monaco where 3,700 changes have been recorded. More than 2,500 value changes have been made in Mexico.
