From the Summary: "This report presents a profile of the membership of the 114th Congress (2015-2016). Statistical information is included on selected characteristics of Members, including data on party affiliation, average age, occupation, education, length of congressional service, religious affiliation, gender, ethnicity, foreign births, and military service. As of June 9, 2015, in the House of Representatives, there are 247 Republicans (including 1 Delegate), 193 Democrats (including 4 Delegates and the Resident Commissioner of Puerto Rico), and 1 vacancy. The Senate has 54 Republicans, 44 Democrats, and 2 Independents, who both caucus with the Democrats. The average age of Members of the House at the beginning of the 114th Congress was 57.0 years; of Senators, 61.0 years. The overwhelming majority of Members of Congress have a college education. The dominant professions of Members are public service/politics, business, and law. Most Members identify as Christians, and Protestants collectively constitute the majority religious affiliation. Roman Catholics account for the largest single religious denomination, and numerous other affiliations are represented. The average length of service for Representatives at the beginning of the 114th Congress was 8.8 years (4.4 terms); for Senators, 9.7 years (1.6 terms)."
CRS Report for Congress, R43869
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html