The real reason is a pretty dull one. I'm worried about losing these figures in the sea of numbers. Once you lose track of figures, finding them again is like looking for a lifeboat bobbing about in a great expanse of ocean. Luck and patience are your only hope.
Here are the numbers:
|Scottish beer exports 1850 - 1914 (barrels)|
|Statistics of British commerce by Braithwaite Poole, 1852, page 6|
|Brewers' Almanack 1928, p. 115|
|A History of the Brewing Industry in Scotland by Ian Donnachie, 1998, page 152.|
Not much to say except: look at those boom years after 1885. What's interesting is that Scottish beer production peaked in 1900, but exports continued to increase right up until WW I. Which means that exports must have been increasingly important to Scottish brewers.
It's a shame I don't have a matching set of UK exports. Because it looks as if Scotland lagged behind England in exports until 1889, then made a quick spurt at the end of the 19th century to pass England. At least in percentage terms. Scotland would have to wait until the 1920's to overtake England in absolute numbers.
A word of warning about the figures. It's not clear whether those after 1880 are standard or bulk barrels. Except for the UK 1900 figure. That's definitely standard barrels. There shouldn't be too much difference between standard and bulk barrels in this period, as average gravity was close to 1055º.