Board Thread:Bloons Wiki and BTD News/@comment-5436357-20121226203614/@comment-3153244-20130425074730

One thing is - just because your defense can probably beat Round 200 doesn't mean it can do the same for 300, or 350. As rounds progress, bloons become progressively faster, and blimps become progressively harder to pop. The blimps on Round 86 are already considerably harder to pop than the ZOMG on Round 85. Someone on the NK forums made an Excel spreadsheet on calculating these values; I can find it for you if you're interested. The bolded sections of my post have been mentioned by Aaron, which is how I, along with a whole bunch of people on the forums who read Aaron's post, know.

EDIT:

Link to file Link to page
 * http://www.mediafire.com/?my9bwd513z5kzjr
 * http://archive.ninjakiwi.com/Forum/showthread.php/17692-Rohan-s-Complete-Freeplay-Guide