use List::Util qw{ sum };

for my $report (values %counts) {
    my $sum = sum(values %$report);
    $_ = sprintf '%.2f', 100 * $_ / $sum for values %$report;
}
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So, no need for %overallcounts.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]