Why lowercase letters save data

... one of my favorite prop bets is to bet that<p><pre><code> sort X | gzip -9 &gt; sorted.gz </code></pre> will make a smaller file than<p><pre><code> gzip -9 X &gt; not-sorted.gz </code></pre> for any text file, particularly something like a CSV. Much like lowercasing, it works almost every time.