[1]There are usually many sources of data for international comparison in comparative studies of the development stages of different economies, such as Madison’s data of world economic history, Palgrave's world history statistics, World Bank's WDI database, IMF's WEO database, and OECD's national accounts data. Among these, renowned economic historian Madison's data of world economic history, which are highly authoritative and widely acknowledged, can meet the need for comparison between different countries and periods over a long time. Madison's data have been obtained by means of purchasing power parity and international multilateral comparison, with the 1990 level as the benchmark and the 1990 international dollar as the basic unit. All the GDP and per capita GDP data in this paper are from Madison's database and measured in the 1990 international dollar.