General rule of thumb: whenever you find yourself creating a collection of variables, you should use a hash (or occasionally an array) instead. Also, when you find yourself using a C-style 'for(;;)' loop, you should consider whether it's actually the right thing. Most times, it's not.

### Array
# Indexes of 0-4 automatically assigned by Perl!
my @kpi = qw/10 20 30 40/;
print "line$kpi[$_]\n" for 0..4;

### Hash
my %kpi;
# Populating via hash slice to save typing
@kpi{0..4} = qw/10 20 30 40 50/;
print "line$kpi{$_}\n" for 0..4;
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