JW facts calls it percentage that stopped publishing compared to number baptised on his page. I find the breakout by country you did interesting Cedars. Paul looked at a number of different measures on his website:
http://www.jwfacts.com/watchtower/statistics.php
It's hard to measure but the bottom line trend is not promising for the WTS. If the trend continues, they will enter into a period of net decline. The % increase in publishers is down (growth but less growth), the actual number increase in publishers is down and baptisms are down both in raw numbers as well as % of average publishers.
00DAD has some interesting questions and I'm not sure even the WTS has the answers to those, although I would think they would find it pretty helpful in their retention efforts if they did. I do recall hearing at somewhere around 50% of DF'ed eventually come back but not sure if there's any validity to that. I would say the number who DA returning are practically nil. I would also venture to guess that based on my somewhat limited experience, the ratio of DF to DA is probably like 95% DF and 5% DA. It still is news when someone around here DAs.
I also believe that the number of baptisms as a percentage of publishers took a major nose dive as a result of the 95 generation change. The effect of that on the urgency level of the rank and file JW while sublimal was important since that was the first time many started to realize that they were going to retire and likely die in "this system".