title: Compression ratios for different zlib compression levels
body: <p>I am considering what level of zlib compression to use, and I am curious about the different compression rates for the different compression levels that can be specified in zlib commands. The <a href="http://www.zlib.net/manual.html#Constants" rel="noreferrer">zlib manual</a> has the following constants for specifying the compression level:</p>
  
  <pre><code>#define Z_NO_COMPRESSION         0
  #define Z_BEST_SPEED             1
  #define Z_BEST_COMPRESSION       9
  #define Z_DEFAULT_COMPRESSION  (-1)
  </code></pre>
  
  <p>Clearly, a lower the number means lower latency for compression and deflation at the cost of a less-compressed file, while a higher number favors better compression at the cost of higher latency.</p>
  
  <p>My question is, <strong>what compression ratios can be expected for the different compression levels?</strong> This <a href="http://www.zlib.net/zlib_tech.html" rel="noreferrer">zlib web page</a> says, <em>More typical zlib compression ratios are on the order of 2:1 to 5:1</em> in the context of maximum compression, but are there also compression ratios / ranges for the other compression factors as well?</p>