Here we go:
1. statistics of the all admissions rates in 2017
https://www.canada.ca/content/dam/ircc/migration/ircc/english/pdf/pub/annual-report-2017.pdf
From which all H&C accepted immigrants were 3913 people (attention those are not approved application as you can have more than 1 person on one application).
That also includes H&C cases where people did not meet their RO requirement, H&C for spouses and children or parents.
Now here is the part of the statistics about appeals.
http://www.irb-cisr.gc.ca/Eng/ImmApp/stats/Pages/index.aspx
What Is a bit problematic, is to distinguish between H&C cases and others.
From this one it is visible, that the highest success rates have sponsorships appeals. (app. 40%)
Removal orders (including refugee removal orders) have app. 20% success rate. bear in mind that they do also include removal order for those that did not meet RO criteria.
This data also contains mix of standard appeal and H&C appeals (which are usually last resort).
So the reality of H&C approvals for refugees lies somewhere between 10 and 20%.
In some cases people will reconsider and withdraw their appeal and in others they will just abandon it. (many of which are appeals without much chance for success).
So, the measurement here appears to be what % of people landed were out of the H&C bucket compared to all other landings? That doesn't tell us the approval rate at stage 1 or 2 though. There is no H&C application appeal process but there are H&C considerations within Appeals so this adds confusion.
If you find any place that tells you approval rates at stage 1 (and 2 if you can find them) then I'd be confident that you may be right. As it is, I don't think so. No malice here, but I do believe that they are very likely approved at a higher rate than your stitching together of the landing number breakdown.