I have no idea since I've never had an HF phone or CW contact in over 10 years much less have logged them. In fact I can tell you my last two SSB contacts. Around 20 years abo, both mobile and not planned, believe it or not. Discechio (sp) Island and Pitcairn Island. Both DXpeditions. Never bothered to even QSL. Shows how excited I get over DXpeditions.
So I don't have access to any data. I'd love for the ARRL to give me a week of read-only query privileges. It'd be fun to crunch the data for trends. My guess is the confirmation rate for CW and Phone is much lower since it requires some manual entry. I suspect Award hunters do it religiously but the vast majority of rag chewers and net'ers probably don't unless asked. My observation on much of HF phone and CW, as well as local VHF/UHF is that it's all very cliquish. Don't get me started on the U/V satellite FM transponder traffic. I gave up after a couple of attempts because it was the same two hams hogging every southeastern pass. Us digital dudes don't want to socialize. We just want to rack up the contacts and sometimes the awards.