http://www.uesp.net/wiki/Morrowind:Demographics
http://www.uesp.net/wiki/Skyrim:Demographics
Basically, the graphs provided here show the difference populations of each town, settlement, and city of Morrowind, and each 'city' in Skyrim. And it kind of goes to prove the point that Skyrim seems empty, and devoid compared to Morrowind. Not only do NPC's say less things, there are less NPC's. To give some context, Morrowind's largest city - Vivec contains more people than Solitude, Riften, Whiterun, and Markarth combined. Both graphs (appropriately, I think) include guards in their numbers.
So, I just thought this was really interesting and decided to share.