Normalizing histograms and Finding best fit distribution

[shegal]

I have plotted packets arriving in one second at a router. I then made histograms of the number of occurences of same number of packets in one second time window. My question is that I want to normalize these histograms. How can I do this to get probability mass functions. And then how do I check which distributions give the best fit for these histograms.

 

[EnumaElish]

To normalize, you should express the number of packets as percent of the total, so in the end they add up to 100%.

I'd start with the lognormal distribution.