From here some interesting stats:

• 6 million PHP programmers
• According to Linkedin, Facebook currently employs approximately 8850 software developers.
• At Amazon, there are around 36,000 developers writing code.
• Apple employs around 20 million developers, and together they have made about $100 billion in revenues.
• As of now, Netflix employs only 80 software engineers, who build 50 applications.
• According to the official Google employee report, 27,169 software engineers work at Google (i.e. research & development).