"This report presents a profile of the membership of the 115th Congress (2017-2018) as of January 4, 2017. 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. In the House of Representatives, there are 243 Republicans (including 1 Delegate and the Resident Commissioner of Puerto Rico) and 198 Democrats (including 4 Delegates). The Senate has 52 Republicans, 46 Democrats, and 2 Independents, who both caucus with the Democrats. The average age of Members of the House at the beginning of the 115th Congress was 57.8 years; of Senators, 61.8 years, among the oldest in U.S. history."
CRS Report for Congress, R44762
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html