Incidence of '68 DDO Dimes.
I've previously estimated these at about 2.7% in mint sets but am coming to believe this is significantly too high. Since they are much more popular now it's pretty likely they are being cherry picked at a significant rate so any sample might be contaminated.
Be this as it may I now believe it might be as low as 2%.
This is one of my favorite modern varieties because it's easily seen on the "6" of the date yet it mostly escaped notice until this century.
Now that '68 mint sets are getting harder to find perhaps we'll see more interest in it.