This includes all first party Cartoon Network series from 1996-present. Sorry it's not as colorful as I originally made it...
1996
Dexter’s Laboratory (4/27)
New shows: 1
Cancelled shows: 0
Cartoon Cartoon/ Powerhouse Era (18 shows)
1997
Dexter’s Laboratory
Johnny Bravo (7/7)
Cow and Chicken/ I Am Weasel (7/15)
*Powerhouse Era begins on 7/16
New shows: 2
Cancelled shows: 0
Simultaneously running shows: 3
1998
Dexter’s Laboratory
Johnny Bravo
Cow and Chicken/ I Am Weasel
The Powerpuff Girls (11/18)
New shows: 1
Cancelled shows: 0
Simultaneously running shows: 4
1999
Dexter’s Laboratory (reruns)
Johnny Bravo
The Powerpuff Girls
Ed, Edd n’ Eddy (1/4)
I Am Weasel (6/10)
Cow and Chicken/ I Am Weasel (ended 7/24)
Mike, Lu & Og (11/12)
Courage the Cowardly Dog (11/12)
New shows: 4
Cancelled shows: 1
Simultaneously running shows: 6
2000
Dexter’s Laboratory (reruns)
Johnny Bravo
The Powerpuff Girls
Ed, Edd n’ Eddy
I Am Weasel (ended 3/2)
Mike, Lu & Og
Courage the Cowardly Dog
Sheep in the Big City (11/17)
New shows: 1
Cancelled shows: 1
Simultaneously running shows: 6
2001
Johnny Bravo
The Powerpuff Girls
Ed, Edd n’ Eddy
Mike, Lu & Og (ended 5/27)
Courage the Cowardly Dog
Sheep in the Big City
Time Squad (6/8)
Samurai Jack (8/10)
Grim & Evil (8/24)
Dexter’s Laboratory (11/16)
New shows: 3
Cancelled shows: 1
Simultaneously running shows: 9
2002
Dexter’s Laboratory
Johnny Bravo
The Powerpuff Girls
Ed, Edd n’ Eddy
Sheep in the Big City (ended 4/7)
Time Squad
Samurai Jack
Whatever Happened to Robot Jones? (6/25)
Grim & Evil (ended 10/18)
Courage the Cowardly Dog (ended 11/20)
Codename: Kids Next Door (12/6)
New shows: 2
Cancelled shows: 3
Simultaneously running shows: 8
2003
Johnny Bravo
The Powerpuff Girls
Ed, Edd n’ Eddy
Samurai Jack
Codename: Kids Next Door
The Grim Adventures of Billy and Mandy (6/14)
Evil Con Carne (7/11)
Star Wars: Clone Wars (11/7)
Whatever Happened to Robot Jones? (ended 11/14)
Dexter’s Laboratory (ended 11/20)
Time Squad (ended 11/26)
New shows: 3
Cancelled shows: 3
Simultaneously running shows: 8
City Era (6 shows)
2004
The Powerpuff Girls
Ed, Edd n’ Eddy
Codename: Kids Next Door
The Grim Adventures of Billy and Mandy
Star Wars: Clone Wars
Megas XLR (5/1)
*City Era officially begins on 6/14
Foster’s Home for Imaginary Friends (8/13)
Johnny Bravo (ended 8/27)
Evil Con Carne (ended 10/22)
Samurai Jack (ended 10/29)
Hi Hi Puffy AmiYumi (11/19)
New shows: 3
Cancelled shows: 3
Simultaneously running shows: 8
2005
The Powerpuff Girls (ended 3/25)
Ed, Edd n’ Eddy
Codename: Kids Next Door
The Grim Adventures of Billy and Mandy
Star Wars: Clone Wars (ended 3/25)
Megas XLR (ended 4/26)
Foster’s Home for Imaginary Friends
Hi Hi Puffy AmiYumi
The Life and Times of Juniper Lee (5/30)
Camp Lazlo (7/8)
My Gym Partner’s a Monkey (12/26)
Ben 10 (12/27)
New shows: 4
Cancelled shows: 3
Simultaneously running shows: 9
2006
Ed, Edd n’ Eddy
Codename: Kids Next Door
The Grim Adventures of Billy and Mandy
Foster’s Home for Imaginary Friends
*Yes! reface officially begins on 4/3
Squirrel Boy (5/27)
Hi Hi Puffy AmiYumi (ended 6/27)
The Life and Times of Juniper Lee
Camp Lazlo
My Gym Partner’s a Monkey
Ben 10
Class of 3000 (11/4)
New shows: 2
Cancelled shows: 1
Simultaneously running shows: 10
Downhill Era (5 shows)
2007
Ed, Edd n’ Eddy
Codename: Kids Next Door
The Grim Adventures of Billy and Mandy
Foster’s Home for Imaginary Friends
The Life and Times of Juniper Lee (ended 4/9)
Camp Lazlo
My Gym Partner’s a Monkey
Ben 10
*Fall reface officially begins on 9/1
Squirrel Boy (ended 9/27)
Class of 3000
Chowder (11/2)
Transformers: Animated (12/26)
New shows: 2
Cancelled shows: 2
Simultaneously running shows: 10
2008
Ed, Edd n’ Eddy
Codename: Kids Next Door (ended 1/21)
Foster’s Home for Imaginary Friends
Camp Lazlo (ended 3/27)
Ben 10 (ended 4/15)
Ben 10: Alien Force (4/18)
Class of 3000 (ended 5/25)
Chowder
Transformers: Animated
The Marvelous Misadventures of Flapjack (6/5)
*Noods reface officially begins on 7/14
The Secret Saturdays (10/4)
The Grim Adventures of Billy and Mandy (ended 10/12)
My Gym Partner’s a Monkey (ended 11/27)
New shows: 3
Cancelled shows: 6
Simultaneously running shows: 7
Rock Bottom/ CN Real Era (0 shows)
2009
Foster’s Home for Imaginary Friends (ended 5/9)
Chowder
Transformers: Animated (ended 5/23)
Ben 10: Alien Force
The Marvelous Misadventures of Flapjack
The Secret Saturdays
Ed, Edd n’ Eddy (ended 11/8)
New shows: 0
Cancelled shows: 3
Simultaneously running shows: 4
Rehab Era (12 shows)
2010
The Secret Saturdays (ended 1/30)
Ben 10: Alien Force (ended 3/26)
Adventure Time (4/5)
Ben 10: Ultimate Alien (4/23)
Generator Rex (4/23)
*CHECK It reface officially begins on 5/29
Chowder (ended 8/7)
The Marvelous Misadventures of Flapjack (ended 8/31)
Regular Show (9/6)
Sym-Bionic Titan (9/17)
Robotomy (10/25)
New shows: 6
Cancelled shows: 4
Simultaneously running shows: 6
2011
Adventure Time
Ben 10: Ultimate Alien
Generator Rex
Regular Show
Robotomy (ended 1/24)
The Problem Solverz (4/4)
Sym-Bionic Titan (ended 4/9)
The Amazing World of Gumball (5/3)
Secret Mountain Fort Awesome (8/1)
New shows: 3
Cancelled shows: 2
Simultaneously running shows: 7
2012
Adventure Time
Ben 10: Ultimate Alien (ended 3/31)
Generator Rex
Regular Show
The Problem Solverz
The Amazing World of Gumball
Secret Mountain Fort Awesome
Ben 10: Omniverse (9/22)
New shows: 1
Cancelled shows: 1
Simultaneously running shows: 7
2013
Adventure Time
Generator Rex (ended 1/3)
Regular Show
The Problem Solverz (ended 3/30)
The Amazing World of Gumball
Secret Mountain Fort Awesome
Uncle Grandpa (9/2)
Steven Universe (11/4)
New shows: 2
Cancelled shows: 2
Simultaneously running shows: 6
2014
As of 11/15/13:
Most total shows:
2008 (13); 2007,2005 (12); 2006,2004,2003,2002 (11); 2010,2001 (10)
Most new shows:
2010 (6); 2005/1999 (4); 2011,2008,2004,2003,2001 (3)
Most simultaneously running shows:
2007,2006 (10); 2005,2001 (9); 2004,2003,2002 (8)
Most cancelled shows:
2008 (6); 2010 (4); 2009,2005,2004,2003,2002 (3)
Least new shows:
2009 (0); 2012,2000,1998 (1)
Least cancelled shows:
1998 (0); 2012,2006,2001,2000,1999 (2)
Least shows: 1998 (4)
Eras with the most total shows:
Cartoon Cartoon/ Powerhouse Era (18)
Rehab Era (12)
City Era (6)
I had plenty of free time today (as you can see) and was bored so I did some research and put this together in hopes of inspiring some observations and discussions on various things. Notice any patterns? Trends? Any interesting details? Favorite year(s) and why? Feel free to drop any information or the sake of keeping this updated and more in depth! Any information or all other shows that aren't original series but aired in CN are welcome as well.