If your looking to find if this distribution is likely a uniform distribution, this looks like a job for Chi square test.
Dealing with absolute values (updated from "percentages" to meet what I posted): 
Sum of ((observed - expected)^2)/expected)
dividing by df (number of degrees of freedom

[download]
Since you have 19 classes, df = 18 the Chi square statistic is: X-squared = 38297.18, df = 18, p-value < 2.2e-16
And that very small p-value indicates it does not depart significantly from a uniform distribution...
Updated originally got it backwards, as Anonymous Monk pointed out. Hence the following also became a moot point
However if the the same hump was to be observed over and over again, then my suggested approach was probably not the right one to follow, a real statistician might have a better insight. (That last part still holds ;-)

In reply to Re: [OT]: Statistical significance? by jjap
in thread [OT]: Statistical significance? by BrowserUk

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