15% of all passcode sets were represented by only 10 different passcodes (out of a possible 10,000). The implication? A thief (or just a prankster) could safely try 10 different passcodes on your iPhone without initiating the data wipe. With a 15% success rate, about 1 in 7 iPhones would easily unlock--even more if the intruder knows the usersxxx8217; years of birth, relationship status, etc.
Most Common iPhone Passcodes | iPhone | Daniel Amitay