Well, I just did a super-informal and probably somewhat inaccurate investigation relating to Sunday Rusty Riley original art. Of course, there were originally six times as many dailies as Sundays. I was working from a very small sample size.
For the years 1948 through 1954, I noted about Sunday 12 strips (original art) in total. I noted no strips for 1949, 1952, and 1954.
For the years 1955 through 1959, I noted about 31 Sunday strips (original art) in total, at least one for each year (10 for 1957 alone).
For 1948 through 1954 (6.5 years of the Sunday strip): 12 examples.
For 1955 through 1959 (5 years of the Sunday strip): 31 examples.
The only real (but still somewhat tentative) conclusion I reached was that the strip (original art) tends to be more common during the later years.
February 26, 2010