Let's step through this:

foreach (1..100) {
    say rand($_);
}
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When $_ is equal to ...

• ... 1, rand($_) cannot be larger than 1.
• ... 2, rand($_) cannot be larger than 2.
• ... 3, rand($_) cannot be larger than 3.
• ... 4, rand($_) cannot be larger than 4.
• ... 5, rand($_) cannot be larger than 5.
• ... 6, rand($_) cannot be larger than 6.

Look at one of my earlier posts on this thread. The documentation for rand states that 0 <= rand($x) < $x if $x > 0. To accomplish what you are trying to do would require that you do this:

say 1 + rand(99 - 1) for (1..100)
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In my previous node, MAX = 99 and MIN = 1. The 1..100 is the number of iterations you wish to use. If you use rand($_), your results will be biased toward the lower end of the counter range.