Coca-Cola (KO - Get Report) is trying to sell more of its unsweetened offerings both at home and abroad. For example, Coca-Cola Zero Sugar grew unit case volume by double digits in the fourth quarter in Western Europe. And its Smartwater achieved double-digit unit case volume growth during the year in North America. Coke is also trying to mix up its packaging. Here's what the company did to shake things up in the fourth quarter.