You could also read 300 threads from programming / project guidance and count the ones mentioned.
I also miss other options in the list - eclipse - visual studio - commandline makefiles - notepad++ - are also used .
Or use Google as statistics source 
google arduino 0.22 ==> ~425.000 hits
ggole arduino 0.23 ==> ~411.000 hits
google arduino 1.0 ==> ~587.000 hits