How to make a biased random number out of a large set of numbers

I want to make Python 3.7.1 pick a number between 0 and 100. However I want a lower number to be much more likely than a higher number, in a reverse exponential-smooth-graduation-curve kind of way (doesn't have to be exact).

I guess I could start with

myrandomnumber = random.randint(0, 100)

And then link that to an array of some sort to determine differing percentages for each number. I've seen other people do that with random die rolls, but the thing is, that's quite neat for only for six possibilities, I want to do this for a hundred (or more) and don't want to sit there making a huge array with a hundred entries just for that. Of course I could do it this way I suppose, but I feel like Python probably has a really easy way to do this that I'm missing.

Thanks, folks!