From time to time I get questions about the market share and usage of JDeveloper, and I must say it is something that is very hard for us to answer. We know how many downloads we get but downloads don't translate to actual usage.
There are different companies that conduct polls every now or then, but even then the results between them differ quite a lot and we can't find a definitive percentage of usage.
Now TSS are running their own IDE survey. I'll be interested to see the results of this one. Although from knowing the type of developers who are hanging around TSS - mostly hard core coders - I know the results will still not be reflective of the overall market.
In any case go and vote here.