An estimated 11,300 laptop computers, 31,400 handheld computers and 200,000 mobile telephones were left in taxis around the world during the last six months, a survey found on Monday. The survey of some 1,000 taxi drivers said that passengers had lost three times more handheld computers in the second half of 2004 than in 2001, when the research by security software company Pointsec was first carried out.