The 2nd column is the date that the content listed in the 1st column was released. The 3rd column is the date that each of the large or moderate size patches was released (yes, what qualifies as "moderate" vs "small / hot-fix" is my somewhat arbitrary decision.)
Content Patches
Civ V 09/21/10 None
Babylon 10/25/10 10/22/10
Cradle of Civilization 11/30/10 None
Spain & Inca 12/16/10 12/15/10
Polynesia 03/03/11 03/01/11
Explorer's Map Pack & Denmark 05/03/11 04/28/11
None None 06/28/11
Korea & Wonders of the Ancient World 08/11/11 08/11/11
None None 12/20/11
G&K 06/18/12 06/14/12
None None 11/01/12
BNW 07/09/13 07/02/13
Scrambled Continents 10/15/13 10/15/13
Scrambled Nations 11/05/13 None
Though, I think scrambled nations should be lumped in with scrambled continents on 10/15. It's clear they were developed at the same time. The release was broken up for marketing or sales reasons.
Some observations:
1) No content has been developed without an accompanying patch (as I said, I believe Nations & Continents were developed together; also, Cradle of Civ maps were a pre-order bonus).
2) There was only 1 large patch between G&K & BNW. We already had a large post-BNW patch. Seems unlikely we'll get more than 1 more large/medium patch without new content.
3) The period between a DLC release and prior content seems to be approx 3 months, which would put us at 1/15 - 2/05 approx.
4) The expansions were each approx 1yr after the prior content release, which would put us at around July - Nov '14.
Edit: I lined all the columns up nicely in my post, but the formatting seems to have disappeared.
