According to CNET, Linux developers have steadily increased from Linux kernel version 3.0 to version 3.10, about 2 years in between.
It's known that the Linux community is constantly growing, but now we know the rate at which it is growing. It seems that all is going well this year for Linux, News after News.
The fact that were talking about Linux KERNEL developers rather than developers on only a particular Linux OS is also very positive news. See, Kernel Linux developers affect the whole Linux community, therefore they might increase performance and reliability to anyone using Linux.
"This rate of change continues to increase, as does the number of developers and companies involved in the process; thus far, the development process has proved that it is able to scale up to higher speeds without trouble,"
Find the full CNET article here: http://news.cnet.com/8301-1035_3-57603216-94/linux-development-by-the-numbers-big-and-getting-bigger/