use 5.20.0;
use warnings;

use Spreadsheet::Read;

my $sheet  = 1;
my $column = 2;
my @column = @{ReadData ("file.xls")->[$sheet]{cell}[$column]};
while (@column and !defined $column[-1]) {
    pop @column;
    }
say "Column ${column}'s last defined row = ", $#column;