Warty Warthog : 4.10 (2004-10-20)
Hoary Hedgehog : 5.04 (2005-04-08)
Breezy Badger : 5.10 (2005-10-12)
Dapper Drake : 6.06 LTS (2006-06-01)
Edgy Eft : 6.10 (2006-10-26)
Feisty Fawn : 7.04 (2007-04-19)
Gutsy Gibbon : 7.10 (2007-10-18)
Hardy Heron : 8.04 LTS (2008-04-24)
Intrepid Ibex : 8.10 (2008-10-30)
Jaunty Jackalope : 9.04 (2009-04-20)
Karmic Koala : 9.10 (2009-10-29)
Lucid Lynx : 10.04 LTS (2010-04-29)
Maverick Meerkat : 10.10 (2010-10-10)
Natty Narwhal : 11.04 (2011-04-28)
Oneiric Ocelot : 11.10 (2011-10-13)
Precise Pangolin : 12.04 LTS (2012-04-26)
Quantal Quetzal : 12.10 (2012-10-18)
Raring Ringtail : 13.04 (2013-04-25)
Saucy Salamander : 13.10 (2013-10-17)
Trusty Tahr : 14.04 LTS (2014-04-17)
Utopic Unicorn : 14.10 (2014-10-23)
Vivid Vervet : 15.04 (2015-04-23)
Wily Werewolf : 15.10 (2015-10-22)
Xenial Xerus : 16.04 LTS (2016-04-22)
Yakkety Yak : 16.10 (2016-10-13)
Zesty Zapus : 17.04 (2017-04-13)
Artful Aardvark : 17.10 (2017-10-19)
Bionic Beaver : 18.04 LTS (2018-04-26)
Cosmic Cuttlefish : 18.10 (2018-10-18)
Disco Dingo : 19.04 (2019-04-18)
Eoan Ermine : 19.10 (2019-10-17)
Focal Fossa : 20.04 LTS (2020-04-23)
Groovy Gorilla : 20.10 (2020-10-22)
Hirsute Hippo : 21.04 (2021-04-22)
Impish Indri : 21.10 (2021-10-14)
Jammy Jellyfish : 22.04 LTS (2022-04-21)
Kinetic Kudu : 22.10 (2022-10-20)
Lunar Lobster : 23.04 (2023-04-20)
Mantic Minotaur : 23.10 (2023-10-12)
Noble Numbat 24.04 LTS (not yet released)

https://en.wikipedia.org/wiki/Ubuntu_version_history