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I'm trying to optimize my website in consideration of the screen resolutions most commonly used by visitors. &nbsp;However, my Google Analytics data seems to say that the greatest proportion of visitors have an unknown screen resolution (screenshot embedded). &nbsp;How can I interpret this?<br />
<a href="https://filedb.experts-exchange.com/incoming/2011/09_w38/500851/Screen-resolutions.jpg" target="_blank" class="file-inline" title="Google Analytics Screen Resolution stats (426 KB)"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><path d="M67.508 468.467c-58.005-58.013-58.016-151.92 0-209.943l225.011-225.04c44.643-44.645 117.279-44.645 161.92 0 44.743 44.749 44.753 117.186 0 161.944l-189.465 189.49c-31.41 31.413-82.518 31.412-113.926.001-31.479-31.482-31.49-82.453 0-113.944L311.51 110.491c4.687-4.687 12.286-4.687 16.972 0l16.967 16.971c4.685 4.686 4.685 12.283 0 16.969L184.983 304.917c-12.724 12.724-12.73 33.328 0 46.058 12.696 12.697 33.356 12.699 46.054-.001l189.465-189.489c25.987-25.989 25.994-68.06.001-94.056-25.931-25.934-68.119-25.932-94.049 0l-225.01 225.039c-39.249 39.252-39.258 102.795-.001 142.057 39.285 39.29 102.885 39.287 142.162-.028A739446.174 739446.174 0 0 1 439.497 238.49c4.686-4.687 12.282-4.684 16.969.004l16.967 16.971c4.685 4.686 4.689 12.279.004 16.965a755654.128 755654.128 0 0 0-195.881 195.996c-58.034 58.092-152.004 58.093-210.048.041z"/></svg>Screen-resolutions.jpg</a>
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Screen-resolutions.jpg

I'm trying to optimize my website in consideration of the screen resolutions most commonly used by visitors.  However, my Google Analytics data seems to say that the greatest proportion of visitors have an unknown screen resolution (screenshot embedded).  How can I interpret this?

Interpretation of Google Analytics screen resolution data

Web development can range from developing the simplest static single page of plain text to the most complex web-based internet applications, electronic businesses, and social network services using a wide variety of languages and standards, including the familiar HTML, JavaScript and jQuery, ASP and ASP.NET, PHP, ColdFusion, CSS, PHP, Flex and Flash, but also the implementation of a broad list of standards including XML, WSDL, SSDL, VoiceXML and many more.