Not sure if this is only fresh visas or includes visa renewals. Because of the country caps in the naturalization process, you have people from some countries have to renew visas again and again while they wait for naturalization. Given that H1b is only 3 years, for companies like Google and Facebook, you could have a situation where they are just trying to retain employees who have been with the company for a while.
You can only renew an H-1b once (as there is a 6 years limit for H-1b). However, if you have an approved I-140 with a priority date in the future (as is often the case with people from India or China) you can keep on extending your H-1b (which doesn't count against the cap).
