Trigger modules 11,11% drop chance each? Hard to believe.

https://preview.redd.it/s7y7cal3pvif1.png?width=1500&format=png&auto=webp&s=1ec906783b800f9dba89a257105fff091431d423

Has anyone noticed something weird with trigger modules drop rates? Those are my trigger modules and as you can see I only have 4 different. I mean, the probability is there but if I roll a 9 sided die in real life 20 times, and repeat that process again and again I doubt I'm going to get something like this anytime soon or ever.