Updated 6/19: OK, some technical difficulties past, you can find the tables with sales estimates for May 2008 here.
My guess at total market size earlier this week was based on a file Diamond distributed to the media that mistakenly included the April market shares under the banner for May; once that was ferreted out, the new figures adjusted the estimate downward. (The market shares listed here on the site and on Newsarama appear to be the correct ones.) Last May was a monster, so the comparatives were going to be hard to hit; there was also one less shipping week this May. In any event, orders were off in all categories against a year ago and all year-to-date categories are now off — though the widest category, overall comics, trade paperback, and magazine orders, is only off 2% year-to-date.
June 2007 was a much slower month than May 2007, so we’ll see how the comparatives work next time. It's beginning to look a bit like 2003, a year when the market seemed to have been catching its breath after a period of stronger growth; we won't know whether that's true for a few months, I shouldn't think. Having observed this market through colossal highs and extreme lows, I always find it's helpful to get a good number of data points before drawing many conclusions.
With Diamond trade paperback indexed reporting stretching back to early 1998, we can now also do ten-year comparisons. To preserve apples-to-apples, I only compare the number of titles Diamond had on its list in each year; the top 50 in 2003, the top 25 in 1998. There's probably something to be said for the dollars realized by the Top 25 trades more than doubling 10 years later, as we see below.
TOP 300 COMICS UNIT SALES
May 2008: 7.06 million copies
Versus 1 year ago this month: -9%
Versus 5 years ago this month: +24%
Versus 10 years ago this month: +1%
YEAR TO DATE: 32.88 million copies, -7% vs. 2007
TOP 300 COMICS DOLLAR SALES
May 2008: $23.12 million
Versus 1 year ago this month: -6%
Versus 5 years ago this month: +47%
Versus 10 years ago this month: +36%
YEAR TO DATE: $104.36 million, -6% vs. 2007
TOP 100 TRADE PAPERBACK DOLLAR SALES
May 2008: $5.06 million
Versus 1 year ago this month: -17%
Versus 5 years ago this month, just the Top 50 vs. the Top 50: +60%
Versus 10 years ago this month, just the Top 25 vs. the Top 25: +140%
YEAR TO DATE: $21.91 million, -5% vs. 2007
TOP 300 COMICS + TOP 100 TRADE PAPERBACK DOLLAR SALES
May 2008: $28.18 million
Versus 1 year ago this month: -8%
Versus 5 years ago this month, counting just the Top 50 TPBs: +48%
YEAR TO DATE: $126.63 million, -8% vs. 2007
OVERALL DIAMOND SALES (including all comics, trades, and magazines)
May 2008: $36.79 million ($40.66 million with UK)
Versus 1 year ago this month: -10%
Versus 5 years ago this month: +55%
YEAR TO DATE: $171.03 million, -2% vs. 2007, +46% vs. 2003
The graphic charts will be updated soon.