No. .DE is the largest ccTLD followed by .UK ccTLD. The .tk ccTLD is a filler to make reports look good. As most domains in .tk are free, from what I remember, it really should not be included in any set of ccTLDs where domains have to be paid for without that qualification.
That's in large measure due to the quality of the inventory moved through Sedo. Of the many names Sedo moves I'll venture that it's only 1 in 50 to 1 in 100 domains reported sold that I pause to think "that buyer got a good deal". Still, it happens . . and it's always been that way.
I'm uncertain how the "10% unreported" plays into your analysis but, based on my own experience, it's likely that most "signficant $$,$$$+" sales fit into that category.
The better domains sell themselves so that tends to skew the values "reported" as the sellers and buyers in "private sales" have little to gain by reporting their transactions to the world.