Well, if you do go with your approach, you'd have to reorder the set to match how you create output. Hint: you create output row by row (as in, every cell in one row before starting on the next row) rather than column by column.
In your example above, you will in other words need to output Country 1, Countr 9, Country 17 etc, until the first row is done, and then you start on Country 2, Country 10 etc. Take your alphabetically ordered set, and reorder it according to this output order and you will have no problems.
Well, until you get 61 countries in the set instead of 60. Does the 61st country go in a new column? Or should the last column have an extra country. Or should the first column have an extra column - and also cause your entire set to be ordered differently, starting with country10 in the second column etc.