By the Numbers: Longest-serving members of Congress June 7, 2013 -- Updated 1904 GMT (0304 HKT) Rep. John Dingell became longest-serving member of Congress on Friday Dingell's record eclipses that of former Sen. Robert Byrd of West Virginia Contrast that with the 60 days that Dean Barkley served to finish Paul Wellstone's term Dingell and his father, John Dingell Sr., served a total of 80 years in Congress (CNN) -- Rep. John Dingell of Michigan became the longest-serving member of Congress on Friday with 57 years, five months, 27 days and counting on Capitol Hill. His longevity record eclipses that of the late Sen. Robert Byrd of West Virginia. Here's a look at congressional tenure, by the numbers: 9.1 years: Average length of service in the United States House of Representatives as of January 2013, according to the Congressional Research Service. 10.2 years: Average length of service in the U.S. Senate as of January 2013. 13.4 years: Peak average length of service in the House in the 111th Congress (2009-2010). 37: Percent of congressmen in the 113th Congress that have between 0 and 8 years of experience. 20, 11: Average percentage of members of Congress who haven't sought re-election, in the 20th and 21st centuries. 51 years, 5 months, 26 days: Length of time Robert Byrd, D-West Virginia, served in the Senate -- January 3, 1959-June 28, 2010. 6 years: Length of time Byrd served in the House -- January 3, 1953-January 3, 1959. 57 years, 5 months, 27 days: Length of time Rep. John Dingell, Jr., D-Michigan, has served in the House -- December 13, 1955-present. 22 years 6 months 17 days: Length of time his father, Rep. John Dingell Sr., served in the House -- March 3, 1933-September 19-1955. 38 years 5 months, 5 days: Length of service for Sen. Patrick Leahy, D-Vermont, the longest currently serving senator -- January 3, 1975-present. 60 days: Term of former Sen. Dean Barkley, D-Minnesota. He was appointed to the seat of Sen. Paul Wellstone, who was killed in a plane crash in 2002. 36 years, 5 months, 5 days: Length of congressional service for Sen. Barbara Mikulski, D-Maryland, longest-serving female. She served five terms in the House and is in her fifth term in the Senate -- January 3, 1977-January 3, 1987, in the House; January 3, 1987-present in the Senate. 25: Times John Conyers, D-Michigan, has been elected to Congress. He is the longest-serving African-American in congressional history. Conyers was first elected in 1964. 51: Senators in the 113th Congress who had previously served in the House.