Statistic #1: Some studies have found that 41% of preschoolers with an anxiety disorder are still impaired by the condition 4 years later. (Kluger, 2011) So while many kids can outgrow or overcome an anxiety disorder, in other cases it will not go away on its own.
Statistic #2: Kids tend to endure more anxiety than their parents assume they do. A 2009 survey by the American Psychological Association found that 28% of teens and 14% of tweens said they "worried a lot" or "a great deal," and to an extent far greater than what their parents were aware of. (Jensen, 2013)
Statistic #3: According to a 3013 report by the CDC, about 1.8 million children under the age of 18 have anxiety disorders. Some studies also suggest that as many as 10% of children suffer from specific phobias. (Landro, 2013)