Nearly 2,000 developers started contributing to Linux in the past 15 months, making up nearly half of all developers writing code for the open source operating system kernel.

The new developers are helping fuel an ever-bigger Linux community, according to the latest Linux Kernel Development report, which will be released today by the Linux Foundation. The report is expected to be available at this link.

"The rate of Linux development is unmatched," the foundation said in an announcement accompanying the report. "In fact, Linux kernel 3.15 was the busiest development cycle in the kernel’s history. This rate of change continues to increase, as does the number of developers and companies involved in the process. The average number of changes accepted into the kernel per hour is 7.71, which translates to 185 changes every day and nearly 1,300 per week. The average days of development per release decreased from 70 days to 66 days."

Linux is getting more first-time contributors with nearly every release:

"That adds up to 1,963 first-time developers over the course of about fifteen months," the report states. "Remember that 4,171 developers overall contributed to the kernel during this time; one can thus conclude that nearly half of them were contributing for the first time. Many of those developers will get their particular fix merged and never be seen again, but others will become permanent members of the kernel development community."

These numbers cover the period since the last report issued in September 2013. The total number of developers contributing to Linux has risen since then, which identified 3,738 individual contributors over a slightly longer time frame than the period covered in today's report.

Some developers work on their own time, but the majority of Linux developers get paid for their work, and that majority is increasing. "[E]ven if one assumes that all of the 'unknown' contributors were working on their own time, well over 80 percent of all kernel development is demonstrably done by developers who are being paid for their work," the report states.

The report also ranks the top contributors by company.

The "None" figure includes developers working on their own without corporate sponsorship, while "unknown" covers developers for whom a corporate affiliation could not be determined.

Intel and Red Hat have swapped positions since late 2013, when Red Hat was #1 ahead of Intel. Intel also leads the way in bringing new developers on board:

An outreach program for women also brought 24 new developers into the Linux community, the report said.

Each Linux release includes more than 10,000 patches from more than 1,400 developers and more than 200 corporations. "Since the 2.6.11 release, the top ten developers have contributed 36,664 changes—8.2 percent of the total. The top thirty developers contributed just over 17 percent of the total," the report said.

Here's a look at the top individual developers ranked by number of contributed changes:

Linux creator Linus Torvalds doesn't appear on that list, though he still oversees all development and makes the call on when a new version is ready. Top developers like Torvalds "spend much of their time getting other developers’ patches into the kernel; this work includes reviewing changes and routing accepted patches toward the mainline," the report said.

Greg Kroah-Hartman, the developer responsible for Linux kernel stable releases, once again led in "non-author signoffs."

"These additional signoffs are usually an indication of review by a subsystem maintainer. Analysis of signoff lines gives a picture of who admits code into the kernel—who the gatekeepers are," the report states.

Kroah-Hartman led the way with 13,028, 14.4 percent of the total. Another 11 developers contributed at least 1,000 non-author signoffs each.

"The total number of patches signed off by Linus Torvalds (329, or 0.4 percent of the total) continues its long-term decline," the report said. "That reflects the increasing amount of delegation to subsystem maintainers who do the bulk of the patch review and merging."

Since 2005, 11,800 individuals from nearly 1,200 companies have contributed to Linux. The latest numbers give the Linux Foundation reason for optimism. "There are enough companies participating to fund the bulk of the development effort, even if many companies which could benefit from contributing to Linux have, thus far, chosen not to," the report said. "With the current expansion of Linux in the server, desktop, mobile and embedded markets, it’s reasonable to expect this number of contributing companies—and individual developers—will continue to increase."