"Alexa.com maintains a list of the most visited sites on the internet. Here are the ten most popular sites, and the colors that they use. This visualization doesn't include colors used in images, only CSS and HTML color codes. Browsers recognize colors in six different formats; hexadecimal, RGB, RBGA, HSL, HSLA, and predefined color names. Only 4 of the six color formats were used by these sites." Check out this article by Paul Hebert to see all of the details:
I plan to rescrape the data on a regular basis. Because of this, I'll keep analysis to a minimum, since it could become outdated when the data changes. Once I have data over a larger time period I'll be able to examine and graph trends in web development.