Funny, I didn't see anything official in that Kantar report (which was widely published, so most of those "hits" you talk about in Google are just reprinting the same bogus numbers). All they say is that the S7 had 16% of the US market while the iPhone has 14.6%.
In order to determine percentages you need to know actual sales numbers. But Kantar didn't publish those and I can't find their methodology. So most likely it's based on a survey of some kind (perhaps sales from carrier stores or even direct surveys of customers). And percentages of a market without actual real hard numbers is meaningless.
http://m.koreaherald.com/view.php?ud=20160707000313&RURL=#jyk
This article (which was also widely reprinted) claims 26 million S7 sales since it launched. Take out the (almost) 3 weeks it was on sale in the previous quarter ending in March, and the fact Samsung themselves reported record pre-orders in many areas, then it's obvious they sold significantly less than 26 million in the most recent quarter. Even if they sold the same every week and there was no pre-order rush, then we'd be looking at 21 million tops in the recent quarter. So let's be generous and use that number.
So a brand-new flagship (Galaxy S7) being sold for the first 3 months & 3 weeks after launch (when demand is highest) is about half of what Apple sold 9 months after their latest iPhone came out. Please explain how this is impressive?