An updated liste of all the Vocaloid release dates, I'll try to update as new ones come out.
Vocaloid 1
Leon - January 15, 2004
Lola - January 15, 2004
Miriam - July 1, 2004
Meiko - November 5, 2004
Kaito - February 17, 2006
Vocaloid 2
Sweet Ann - June 29, 2007
Miku Hatsune - August 31, 2007
Rin Kagamine - December 27, 2007
Len Kagamine - December 27, 2007
Prima - January 14, 2008
Gakupo Kamui - July 31, 2008
Luka Megurine - January 30, 2009
Gumi - June 26, 2009
Sonika - July 14, 2009
SF-A2 Miki - December 4, 2009
Yuki Kaai - December 4, 2009
Kiyoteru Hiyama - December 4, 2009
Big Al - December 22, 2009
Tonio - July 14, 2010
Lily - August 25, 2010
VY1 - September 1, 2010
Gachapoid - October 8, 2010
Iroha Nekomura- October 22, 2010
Piko - December 8, 2010
VY2 - April 25, 2011
Vocaloid 3
Mew - October 21, 2011
SeeU - October 21, 2011
Tone Rion - December 16, 2011
Oliver - December 21, 2011
CUL - December 22, 2011
Yukari Yuzuki - December 22, 2011
Bruno - December 24, 2011
Clara - December 24, 2011
IA - January 27, 2012
Lapis Aoki- April 6, 2012
Tianyi Luo- July 12, 2012
Galaco - August 5th, 2012
Mayu - December 5th, 2012
Avanna - December 22nd, 2012
ZOLA PROJECT (WIL, YUU, KYO) - June 20th, 2013
Yan He - July 11th, 2013
YOHIOloid - September 10th, 2013
MAIKA - December 18th, 2013
Merli - December 24th, 2013
Macne Nana - January 31, 2014
kokone - February 14, 2014
anon - March 3rd, 2014
kanon - March 3rd, 2014
v fleur - May 9th, 2014
Tohoku Zunko - June 5th, 2014
Chika - October 16th, 2014
Please let me know if I missed any ou got one wrong!
Vocaloid 1
Leon - January 15, 2004
Lola - January 15, 2004
Miriam - July 1, 2004
Meiko - November 5, 2004
Kaito - February 17, 2006
Vocaloid 2
Sweet Ann - June 29, 2007
Miku Hatsune - August 31, 2007
Rin Kagamine - December 27, 2007
Len Kagamine - December 27, 2007
Prima - January 14, 2008
Gakupo Kamui - July 31, 2008
Luka Megurine - January 30, 2009
Gumi - June 26, 2009
Sonika - July 14, 2009
SF-A2 Miki - December 4, 2009
Yuki Kaai - December 4, 2009
Kiyoteru Hiyama - December 4, 2009
Big Al - December 22, 2009
Tonio - July 14, 2010
Lily - August 25, 2010
VY1 - September 1, 2010
Gachapoid - October 8, 2010
Iroha Nekomura- October 22, 2010
Piko - December 8, 2010
VY2 - April 25, 2011
Vocaloid 3
Mew - October 21, 2011
SeeU - October 21, 2011
Tone Rion - December 16, 2011
Oliver - December 21, 2011
CUL - December 22, 2011
Yukari Yuzuki - December 22, 2011
Bruno - December 24, 2011
Clara - December 24, 2011
IA - January 27, 2012
Lapis Aoki- April 6, 2012
Tianyi Luo- July 12, 2012
Galaco - August 5th, 2012
Mayu - December 5th, 2012
Avanna - December 22nd, 2012
ZOLA PROJECT (WIL, YUU, KYO) - June 20th, 2013
Yan He - July 11th, 2013
YOHIOloid - September 10th, 2013
MAIKA - December 18th, 2013
Merli - December 24th, 2013
Macne Nana - January 31, 2014
kokone - February 14, 2014
anon - March 3rd, 2014
kanon - March 3rd, 2014
v fleur - May 9th, 2014
Tohoku Zunko - June 5th, 2014
Chika - October 16th, 2014
Please let me know if I missed any ou got one wrong!