The upper graph shows the absolute frequencies of the numbers thrown as a histogram. The lower graph shows the relative frequency of the event "6" is rolled. For growing numbers of attempts this value stabilizes at 1 / 6≈16,66%.
At the same time this is an empirical proof of the strong law of large numbers for binomial random variables: With increasing sample size the means of the random variables converges to the expected value which here is 1/6.
Absolute frequency 

Relative frequency of the event "6"The expected relative frequency of the event "6" is 16,66%. 