From a Scientific American Article
Most people believe that they are above average, a statistical impossibility. The above average effects, as they are called, are common. For example, 93 percent of drivers rate themselves as better than the median driver. Of college professors, 94 percent say that they do above-average work. People are unrealistically optimistic about their own health risks compared with those of other people. For example, people think that they are less susceptible to the flu than others. Stock pickers think the stocks they buy are more likely to end up winners than those of the average investor. If you think that self-enhancement biases exist in other people and they do not apply to you, you are not alone. Most people state that they are more likely than others to provide accurate self-assessments.