| Patrick J. Leahy, D-Vt. | Jan. 3, 1975 |
| Orrin G. Hatch, R-Utah | Jan. 3, 1977 |
| Max Baucus, D-Mont. | Dec. 15, 1978 |
| Thad Cochran, R-Miss. | Dec. 27, 1978 |
| Carl Levin, D-Mich. | Jan. 3, 1979 |
| Charles E. Grassley, R-Iowa | Jan. 3, 1981 |
| Tom Harkin, D-Iowa | Jan. 3, 1985 |
| Mitch McConnell, R-Ky. | Jan. 3, 1985 |
| Jay Rockefeller, D-W.Va. | Jan. 15, 1985 |
| Barbara A. Mikulski, D-Md. | Jan. 3, 1987 |
| Richard C. Shelby, R-Ala. | Jan. 3, 1987 |
| John McCain, R-Ariz. | Jan. 3, 1987 |
| Harry Reid, D-Nev. | Jan. 3, 1987 |
| Dianne Feinstein, D-Calif. | Nov. 4, 1992 |
| Barbara Boxer, D-Calif. | Jan. 3, 1993 |
| Patty Murray, D-Wash. | Jan. 3, 1993 |
| James M. Inhofe, R-Okla. | Nov. 16, 1994 |
| Ron Wyden, D-Ore. | Feb. 6, 1996 |
| Pat Roberts, R-Kan. | Jan. 3, 1997 |
| Richard J. Durbin, D-Ill. | Jan. 3 1997 |
| Tim Johnson, D-S.D. | Jan. 3, 1997 |
| Jack Reed, D-R.I. | Jan. 3, 1997 |
| Mary L. Landrieu, D-La. | Jan. 3, 1997 |
| Jeff Sessions, R-Ala. | Jan. 3, 1997 |
| Susan Collins, R-Maine | Jan. 3, 1997 |
| Michael B. Enzi, R-Wyo. | Jan. 3, 1997 |
| Charles E. Schumer, D-N.Y. | Jan. 3, 1999 |
| Michael D. Crapo, R-Idaho | Jan. 3, 1999 |
| Bill Nelson, D-Fla. | Jan. 3, 2001 |
| Thomas R. Carper, D-Del. | Jan. 3, 2001 |
| Debbie Stabenow, D-Mich. | Jan. 3, 2001 |
| Maria Cantwell, D-Wash. | Jan. 3, 2001 |
| Lisa Murkowski, R-Alaska | Dec. 20, 2002 |
| Saxby Chambliss, R-Ga. | Jan. 3, 2003 |
| Lindsey Graham, R-S.C. | Jan. 3, 2003 |
| Lamar Alexander, R-Tenn. | Jan. 3, 2003 |
| John Cornyn, R-Texas | Jan. 3, 2003 |
| Mark Pryor, D-Ark. | Jan. 3, 2003 |
| Richard M. Burr, R-N.C. | Jan. 3, 2005 |
| Tom Coburn, R-Okla. | Jan. 3, 2005 |
| John Thune, R-S.D. | Jan. 3, 2005 |
| Johnny Isakson, R-Ga. | Jan. 3, 2005 |
| David Vitter, R-La. | Jan. 3, 2005 |
| Robert Menendez, D-N.J. | Jan. 18, 2006 |
| Benjamin L. Cardin, D-Md. | Jan. 3, 2007 |
| Bernard Sanders, I-Vt. | Jan. 3, 2007 |
| Sherrod Brown, D-Ohio | Jan. 3, 2007 |
| Bob Casey, D-Pa. | Jan. 3, 2007 |
| Bob Corker, R-Tenn. | Jan. 3, 2007 |
| Claire McCaskill, D-Mo. | Jan. 3, 2007 |
| Amy Klobuchar, D-Minn. | Jan. 3, 2007 |
| Sheldon Whitehouse, D-R.I. | Jan. 3, 2007 |
| Jon Tester, D-Mont. | Jan. 3, 2007 |
| John Barrasso, R-Wyo. | June 25, 2007 |
| Roger Wicker, R-Miss. | Dec. 31, 2007 |
| Mark Udall, D-Colo. | Jan. 3, 2009 |
| Tom Udall, D-N.M. | Jan. 3, 2009 |
| Mike Johanns, R-Neb. | Jan. 3, 2009 |
| Jeanne Shaheen, D-N.H. | Jan. 3, 2009 |
| Mark Warner, D-Va. | Jan. 3, 2009 |
| Jim Risch, R-Idaho | Jan. 3, 2009 |
| Kay Hagan, D-N.C. | Jan. 3, 2009 |
| Jeff Merkley, D-Ore. | Jan. 3, 2009 |
| Mark Begich, D-Alaska | Jan. 3, 2009 |
| Michael Bennet, D-Colo. | Jan. 22, 2009 |
| Kirsten Gillibrand, D-N.Y. | Jan. 27, 2009 |
| Al Franken, D-Minn. | July 7, 2009 |
| Joe Manchin III, D-W.Va. | Nov. 15, 2010 |
| Chris Coons, D-Del. | Nov. 15, 2010 |
| Mark S. Kirk, R-Ill. | Nov. 29, 2010 |
| Dan Coats, R-Ind. | Jan. 3, 2011 |
| Roy Blunt, R-Mo. | Jan. 3, 2011 |
| Jerry Moran, R-Kan. | Jan. 3, 2011 |
| Rob Portman, R-Ohio | Jan. 3, 2011 |
| John Boozman, R-Ark. | Jan. 3, 2011 |
| Patrick J. Toomey, R-Pa. | Jan. 3, 2011 |
| John Hoeven, R-N.D. | Jan. 3, 2011 |
| Marco Rubio, R-Fla. | Jan. 3, 2011 |
| Ron Johnson, R-Wis. | Jan. 3, 2011 |
| Rand Paul, R-Ky. | Jan. 3, 2011 |
| Richard Blumenthal, D-Conn. | Jan. 3 2011 |
| Mike Lee, R-Utah | Jan. 3, 2011 |
| Kelly Ayotte, R-N.H. | Jan. 3, 2011 |
| Dean Heller, R-Nev. | May 9, 2011 |
| Brian Schatz, D-Hawaii | Dec. 27, 2012 |
| Tim Scott, R-S.C. | Jan. 3, 2013 |
| Tammy Baldwin, D-Wis. | Jan. 3, 2013 |
| Jeff Flake, R-Ariz. | Jan. 3, 2013 |
| Joe Donnelly, D-Ind. | Jan. 3, 2013 |
| Christopher S. Murphy, D-Conn. | Jan. 3, 2013 |
| Mazie K. Hirono, D-Hawaii | Jan. 3, 2013 |
| Martin Heinrich, D-N.M. | Jan. 3, 2013 |
| Angus King, I-Maine | Jan. 3, 2013 |
| Tim Kaine, D-Va. | Jan. 3, 2013 |
| Ted Cruz, R-Texas | Jan. 3, 2013 |
| Elizabeth Warren, D-Mass. | Jan. 3, 2013 |
| Deb Fischer, R-Neb. | Jan. 3, 2013 |
| Heidi Heitkamp, D-N.D. | Jan. 3, 2013 |
| Jeff Chiesa, R-N.J. | June 10, 2013 |
| Edward J. Markey, D-Mass. | July 16, 2013 |
