Codeforces Round 245 (Div. 1) and Codeforces Round 245 (Div. 2) round statistics

Consider the following Div. 1 rounds:

Codeforces Round 236 (Div. 1)
Codeforces Round 238 (Div. 1)
Codeforces Round 239 (Div. 1)

      Registrants Participants
#236:        1011    616 (61%)
#238:        1052    608 (58%)
#239:         774    538 (70%)

At least, 30% of registered users didn't participate in the rounds.
Do you wonder, what they really do? Do they read the problem statements or not?

Codeforces Round 244 (Div. 2) round statistics

Codeforces Round #243 Statistics

Codeforces Round 243 (Div. 1) and Codeforces Round 243 (Div. 2) round statistics

Codeforces Round 241 (Div. 2) round statistics

Codeforces Round 240 (Div. 1) and Codeforces Round 240 (Div. 2) round statistics

Codeforces Round 239 (Div. 1) and Codeforces Round 239 (Div. 2) round statistics

Codeforces Round 238 (Div. 1) and Codeforces Round 238 (Div. 2) rating change tables

Codeforces Round 238 (Div. 1) and Codeforces Round 238 (Div. 2) round statistics

Codeforces Round 237 (Div. 2) round statistics

Codeforces Round 236 (Div. 1) and Codeforces Round 236 (Div. 2) round statistics

Codeforces Round 235 (Div. 2) round statistics

Codeforces Round 234 (Div. 2) round statistics

Brief data of Codeforces #229 — #233 Rounds statistics

Codeforces Round 228 (Div. 1) and Codeforces Round 228 (Div. 2) round statistics

Codeforces Round 227 (Div. 2) round statistics

Codeforces Round 226 (Div. 2) round statistics

Codeforces Round 225 (Div. 1) and Codeforces Round 225 (Div. 2) round statistics

Codeforces Round 224 (Div. 2) round statistics

Codeforces Round 223 (Div. 1) and Codeforces Round 223 (Div. 2) round statistics

Good Bye 2013 round statistics

Round statistics sample

Here

Values meaning

Sent — participants count, who made at least one problem submission
Pretest — participants count, who's solution stuck on pretests
Hacked — participants count, who's solution was hacked, and didn't pass hack sample
Systest — participants count, who's solution stuck on system tests
Accepted — participants count, who solved the problem
Attempts — attempts count for the problem
Success % — Accepted count / Attempts count
Severity — average attempts count among participants, who solved the problem
Median Score — median score value for solved problem
Hacks — successful(+) and unsuccessful(-) hacking attempts count (invalid tests and compilation errors are ignored)

Graphic representation of Pretest / Hacked / Systest / Accepted columns.
Right-most value — participants count.

Used stuff

Standing pages parsing: Google Chrome + javascript.
Tables and graphs drawing: Google Charts.
Manual actions: Paint.NET + Notepad++ :)