The data in the graph is from the U.S. Department of Commerce.

This table shows the numbers of Democrats, Republicans, and Independents in the 112th session of the U.S. Congress in 2011.

The blog entry and speech excerpt below discuss the U.S. Supreme Court case of Tinker v. Des Moines (1969).
Blog
In the Tinker v. Des Moines case, the Court ruled that students lawfully exercised their rights when they wore black armbands in school as a protest against the Vietnam War. The ruling stated that school officials were wrong to suspend students from school for their act of protest. Students are not required to give up their rights when they enter a public school, especially freedom of speech, which is the foundation of democracy. These students modeled good citizenship by their actions. In contrast, school representatives placing restrictions on liberty provided a bad example to the future leaders of our country.
Speech
I believe the U.S. Supreme Court ruled correctly in Tinker v. Des Moines. Democracy requires individual expression, debate, and public protest. Still, freedom of speech is not the only issue to be considered when protests occur in public schools. School officials have a responsibility to provide a safe environment that is not disruptive to learning. Individual expression should not interfere with a school's mission to teach.