I have tried to find pf70 silver proof yuan Ming yuan with good price but fail. Price too high and many of my collectors mate in Singapore have given up to own it.
This is a good point that brings perspective to my initial sour grapes knee jerk.
The 2014 Old Summer Palace (YuanMingYuan) has a Silver Proof Mintage: 1000 with Total Graded at NGC: 272 (a little over 1/4th of population) 68 - 95, 69 - 158, 70 - 6.
YuanMingYuan was special because of the extra high relief so low quantities graded at 70 can be easily rationalized along with high pricing and general unavailability.
The 2014 Summer Palace Corridor Silver Proof mintage & total graded are about the same as YuanMingYuan but graded better with 68 - 4, 69 - 174, 70 - 96.
2013 Lan Ting Silver Proof grading was more consistent with what we see quality wise from today's China Mint product with around 1/3rd of mintage (539 out of 1500) graded at 68 - 3, 69 - 249, 70 - 287. More 70's than any other grade...
The Summer Palace Gate's stats are not yet public but the Modern China Mina Quality Trap may have gotten me.

I do not think this concept is valid when applied to the artistic efforts in minting we see with some of the later issues of this series.
FWIW I have not had time to study the Summer Palace Gate but I will be interested in counting how many different surface texture facets it has.
Edit Note: I did not include the 2010 YUYUAN YANGSHAN TANG stats as it was the 1rst and flew under the radar of most for several years. In July of 2012 there were only 4 graded. For completeness sake...
Currently:
SP Mintage: 2010
Total Graded: 445
68 - 92, 69 - 318, 70 - 33