Thanks to reader Joe for making available his count of the number of stamps in the current version of the Blue--i.e., the four part 1997 edition. Even if earlier editions will vary in both number of countries and number of stamps, Joe's data gives us access to additional interesting facts about this series.
To start with the big question: How many stamps are in the Blue Volume 1? Scott/Amos is no longer willing to say. The title page used to state "more than 35,000" spaces but now is silent on the topic. But we know that Scott has been dropping more stamps than adding in recent revisions, so it is not surprising that, according to Joe, the number is currently 34,475. Another way of looking at this, I come up with 58 countries/stamp-issuing-entities that were in the 1943/47 edition but are missing in the 1997 edition. Sounds like a lot, but if you assume each of these averages 10 stamps, then that would only mean a reduction of ~600 (58x10) stamps. I haven't counted, but I would guess the 600 is low (and see the comment below about the US). We should also remember that there are stamps in the post 1947 edition that weren't in the 1943/47. Not a lot, but some.
Now Joe's 34,475 probably doesn't include the free form "blank" pages that Scott includes for certain issues, each of which could hold 50 or so stamps. But there were dedicated "blank" pages in the earlier versions, too, so this shouldn't skew the results too much. Incidentally, I don't think I have ever broken out the "blank" pages in the Blue, so here they are:
US Souvenir Sheets (missing in later editions)
India Convention States
India Feudatory States (missing in later editions)
Italy Offices in the Turkish Empire
Italy Aegean Islands Occupation Stamps (in the 1943/47 edition these were split between two pages; later versions have combined this into one page)
The biggest surprise in the data was which countries were allotted the most spaces. If you had asked me before I saw Joe's spreadsheet, I would have confidently said the US was first. Second would probably have been Germany, and then some combination of France, Austria and, oh, probably Hungary. But I would have been wrong: the US comes in fourth. The top ten countries in order in the 1997 edition are:
1. France 948
2. Germany 801
3. Austria 755
4. United States 729
5. Hungary 620
6. Italy 617
7. Russia 617
8. Salvador 582
9. Nicaragua 569
10. Spain 567
(I should note that the US would have ranked first had Joe used the 1943/47 edition which included more than 300 Revenues, Newspaper stamps, and other issues no longer in the album. This also is a big factor in explaining why the 1997 edition contains under 35,000 stamps.)
Now its interesting to compare the top ten above with the top ten countries ranked by the number of regular issues/commemoratives that are in the Scott Catalog for 1840-1940:
1. United States (#5 in the Blue album's coverage)
2. Iran (Persia) (#15 in the Blue)
3. Turkey (#16 in the Blue)
4. Russia (#7 in the Blue)
5. Mexico (#17 in the Blue)
6. Spain (#11 in the Blue)
7. Nicaragua (#9 in the Blue)
8. Portugal (#14 in the Blue)
9. El Salvador (#8 in the Blue)
10. Hungary (#6 in the Blue)
That is, Iran has the second highest number of regular issues/commems in the Scott catalog but comes in only 15th in terms of the number of spaces provided in the Blue. Since a lot of what we find in old albums for Persia are likely reprints or forgeries, Scott may have done us a favor by providing fewer opportunities to go awry.
I made a rather feeble attempt to look at the comprehensiveness of coverage in the Blue for all countries using my count from the 2007 Scott Classic, but for reasons not worth going into, the following really are only ballpark. Fortunately, Jim is doing this measure accurately in his Blog. Anyway, until he finishes, it looks like two countries in the Blue are complete for every major number: Allenstein and Kionga. A total of 17 countries come in at 75 plus percent completion. At 50% comprehensiveness we are looking at 85 countries. That means that something like 176 countries come in at less than 50% coverage.
I don't know that there is any purpose listing the bottom ten except to answer the trivia question: The country with the fewest spaces is Tahiti with three. Tahiti is also at the bottom in terms of number of possible stamps included in the album: five percent. So apparently pretty scenery and exotic locale were not an influence on the album's editors.
As I have to remind myself whenever I think about comprehensiveness, the Blue is supposed to emphasize affordable stamps. So ideally, if a country in the Blue had spaces for only 1/3 of the stamps in the Catalog, but included every stamp cataloging under $10, then I would think the editors did a good job. So I revisited Michel Bégin's Affordable Classic Stamp website that I blogged about awhile back and imported his information into a database along with Joe's data. This was primarily helpful in that it reminded me how to build relational tables in FileMaker rather than giving much in the way of useful philatelic insights. Nevertheless, 23 countries in the Blue also fall in the Most Affordable Countries category. (Actually, there are more than that but some are Indian Convention States and Italy Aegean Island issues that don't have dedicated spaces in the Blue.) Of the 23 countries with dedicated spaces, Niger comes in at the top. The album is 85% complete for this country which, at the time Bégin compiled his list, had no stamp cataloging more than $3. The other Affordable countries with 50% plus representation were, in order of completeness, Middle Congo, Chad, Italian Colonies, Algeria, Georgia, Mauritania, Eastern Silesia, Ivory Coast, and Haiti. The countries with the fewest spaces, in spite of their being on the Affordable list, were Lebanon, Ethiopia, Memel, Far Eastern Republic, and Azerbaijan, the latter providing spaces for only 9% of the major numbers in the Scott Catalog. This is ironic because anecdotally I think that all of the Blue albums I've seen of any size have most if not all of the spaces filled for Azerbaijan. I've read that this is because they were commonly available in approvals marketed to beginning collectors for many decades.