Smartphone users have grown significantly over the past couple of years, and with more people carrying the expensive high-tech gadgets around, the number of thefts rises as well. According to NPR Boston affiliate WBUR, smartphone manufacturers are doing everything they possibly can to increase the security of their devices for consumers, but theft still runs around the clock.

Matthew Shaer, a journalist investigating black market smartphone thefts, explained to WBUR that as soon as you make a smartphone more difficult to steal in one way, thieves exploit another security flaw and steal devices in a different fashion. Shaer added that it's a constant back and forth between smartphone manufacturers and the black market for stolen devices.

Amount of smartphone users skyrocketing
Recently, Consumer Reports said that in 2009, only 5 percent of the world's population had a smartphone. However, that number has dramatically changed, with analysts expecting roughly 35 percent of the world's population (2.5 billion people to be smartphone owners by the end of 2015.

That figure could continue to change with cheaper smartphones making their way into underprivileged areas of the world. According to WBUR, the increased proliferation of smartphones means a larger pool of thefts. Black market smartphone sales is estimated to be a multibillion-dollar industry, with that figure only growing.

Shaer explained that while single-person thefts are high, the real money in the black market is with not-yet-activated smartphones from vendors, the source stated. These smartphones are much easier to sell in other countries.

"[Not-yet-activated] black market smartphones, because they haven't been activated yet, are worth an incredible amount of money, especially if they can be shipped overseas," said Shaer.

Credit-mule schemes on the rise
In 2012, a FedEx worker reported to the police about a ripped package that held several brand-new iPhones. According to Wired, the police followed the trail of the smartphones, which led them to a Chinese couple who had clean records. The couple were shipping boxes full of brand new iPhones still in their original boxes to an apartment in China.

The couple ran what is called a credit-mule scheme, which involves middlemen in the operation going to different American cities. According to the source, they would reach out to people in homeless shelters and halfway houses and give anyone $100 to get a few on-contract phones from local electronics stores.

The smartphones were obtained for roughly $200 a device and then shipped to China's electronics black market where devices were sold for nearly $1,000. According to Wired, the couple earned almost $2.5 million each year on the plan.

"As long as there are profits to be made, thieves will keep on stealing phones," said Robert Morgester, assistant attorney general heading the eCrime Unit, according to Wired. "I mean, why did Willie Sutton rob banks? Easy: because that's where the money was."

Personal robberies down for iPhones
However, certain technology is helping reduce the amount of personal robberies. According to Venture Beat, the amount of Apple-related robberies was down 19 percent in New York City. That's mainly due to the kill-switch technology that allows users to deactivate their smartphones from their computers at home, which in turn, makes the devices valueless.

While smartphone robberies are going down, it's still absolutely critical to back up electronic devices and have them insured. Personal insurance is a cost-effective strategy to protect all of your devices from the possibility of theft, damage or a lost smartphone. There are personal insurance plans to protect all electronic devices such as laptops, tablets, cameras and smartphones in a single plan to make sure everything a customer owns is safeguarded from potential thieves.