After adding all the sets on Reply #6 on up, I've found that this list has 12 sets of 5 and 15 sets of 6.
Between 5 and 6 seems to be the average number for most-parodied product sets at this time. Originally, it was between 4 and 5.
And, as mentioned above on Reply #21, Wacky Packages has the highest number of releases with 22 (although Cap'n Crunch, Bazooka, Tootsie Roll, Pepsi-Cola, Snickers, Reese's, Planters, Kit Kat, Dunkin' Donuts, Frosted Flakes, Garbage Pail Kids, Charms, Kool-Aid, Play-Doh, Crest and Mr. Clean are all slowly but surely catching up to it, with 20, 19, 14, 13, 12, 12, 12, 11, 11, 10, 10, 10, 10, 10, 10 and 10, respectively). Also, as mentioned above on Reply #37, Gadzooka Bubble Gum is the most individually released Wacky of all with 28 (including one that was unreleased).
Always remember, though, that all of these figures are both subject and likely to change at any time, of course.