Number of $3.99 issues: 22
Percentage of DC's periodicals: 24.2%
Number of $3.99 issues: 70
Percentage of Marvel's periodicals: 68%
Number of $3.99 issues: 0
Percentage of Dark Horse's periodicals: 0%
Number of $3.99 issues: 32
Percentage of IDW's periodicals: 91.4%
Number of $3.99 issues: 7
Percentage of Image's periodicals: 27%
Above numbers do not include collections, variants, or "magazines". Only single issues, almost all of which are 48 pages or less. A 64-pager may have slipped in there somewhere.
Funnily enough, the majority of DC's $3.99 singles are at least 40 pages. Marvel includes 40-48pp singles in the mix, but many $3.99 titles are merely 32pp. Dark Horse, meanwhile, is finding a happy middle ground at $3.50 for all but its most popular titles, which remain at $2.99. Only three IDW singles aren't $3.99, and those are a $2 Parker prelude, a $7.99 Doctor Who annual, and a $9.99 Sam Keith sketchbook.