File:Countries By Percentage Of Protestants 1938.svg
Some countries have percentages. These are countries where Protestant communities may have been more than their level shown on the map given their demographic growth (for example, Czechoslovakia has 0-10% (circa 7.7%), but it could be 10-20%) by 1938; though in several countries percentages are placed just to ensure religious situation there which has been exaggerated by some sources ("10% Protestant" in Lithuania according to an English language source, totally false; a 1932 book by German author K. F. Otto Losch states 3.3% which is far more possible) - this applies to Austria, Poland, Lithuania. To see percentages for blurry cases, look at Canada and Eastern Europe.
Official statistics for France do not exist since it prohibited keeping official religious statistics since 1872. Most probable set of percentages for Western Europe is 0-1% for each country (more closer to 0% than 1%) with possible exceptions of Belgium 3%, France and Luxembourg - both 2%. Note that these are only estimates and not official data.
Note that religion was overall suppressed in the Soviet Union. In 1897, during the Russian Empire which incorporated Finland, Latvia and Estonia, Protestants constituted some 3%.