Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| State | Incumbent | Party | Result | Candidates |
| --- | --- | --- | --- | --- |
| Alabama | Lister Hill | Democratic | Re-elected | Lister Hill (Democratic) Unopposed |
| Arizona | Carl Hayden | Democratic | Re-elected | Carl Hayden (Democratic) 61.4%\nRoss F. Jones (Republican) 38.6% |
| Arkansas | J. William Fulbright | Democratic | Re-elected | J. William Fulbright (Democratic) 83.0%\nBen C. Henley (Republican) 17.0% |
| California | Thomas H. Kuchel | Republican | Re-elected | Thomas H. Kuchel (Republican) 54.0%\nRichard Richards (Democratic) 45.6%\nRay Gourley (Prohibition) 0.4% |
| Colorado | Eugene D. Millikin | Republican | Retired\nDemocratic gain | John A. Carroll (Democratic) 50.2%\nDan Thornton (Republican) 49.8% |
| Connecticut | Prescott S. Bush | Republican | Re-elected | Prescott S. Bush (Republican) 54.8%\nThomas J. Dodd (Democratic) 43.1% |
| Florida | George A. Smathers | Democratic | Re-elected | George A. Smathers (Democratic) Unopposed |
| Georgia | Walter F. George | Democratic | Retired\nDemocratic hold | Herman E. Talmadge (Democratic) Unopposed |
| Idaho | Herman Welker | Republican | Lost re-election\nDemocratic gain | Frank Church (Democratic) 56.2%\nHerman Welker (Republican) 38.7% |
| Illinois | Everett M. Dirksen | Republican | Re-elected | Everett M. Dirksen (Republican) 54.1%\nW. Richard Stengel (Democratic) 45.7% |
| Indiana | Homer E. Capehart | Republican | Re-elected | Homer E. Capehart (Republican) 55.2%\nClaude R. Wickard (Democratic) 44.4% |
| Iowa | Bourke B. Hickenlooper | Republican | Re-elected | Bourke B. Hickenlooper (Republican) 53.9%\nR. M. Evans (Democratic) 46.1% |
| Kansas | Frank Carlson | Republican | Re-elected | Frank Carlson (Republican) 57.9%\nGeorge Hart (Democratic) 40.5% |
| Kentucky | Earle C. Clements | Democratic | Lost re-election\nRepublican gain | Thruston Morton (Republican) 50.4%\nEarle C. Clements (Democratic) 49.7% |
| Kentucky\nSpecial: Class 2 | Robert Humphreys | Democratic | Appointee retired\nWinner elected to finish term ending January 3, 1961\nRepublican gain | John S. Cooper (Republican) 53.2%\nLawrence W. Wetherby (Democratic) 46.8% |
| Louisiana | Russell B. Long | Democratic | Re-elected | Russell B. Long (Democratic) Unopposed |
| Maryland | John M. Butler | Republican | Re-elected | John M. Butler (Republican) 53.0%\nGeorge P. Mahoney (Democratic) 47.0% |
| Missouri | Thomas C. Hennings, Jr. | Democratic | Re-elected | Thomas C. Hennings, Jr. (Democratic) 56.4%\nHerbert Douglas (Republican) 43.6% |
| Nevada | Alan Bible | Democratic | Re-elected | Alan Bible (Democratic) 52.6%\nCliff Young (Republican) 47.4% |
| New Hampshire | Norris Cotton | Republican | Re-elected | Norris Cotton (Republican) 64.1%\nLaurence M. Pickett (Democratic) 35.9% |
| New York | Herbert H. Lehman | Democratic | Retired\nRepublican gain | Jacob K. Javits (Republican) 53.3%\nRobert F. Wagner, Jr. (Democratic) 46.7% |
| North Carolina | Sam J. Ervin, Jr. | Democratic | Re-elected | Sam J. Ervin, Jr. (Democratic) 66.6%\nJoel A. Johnson (Republican) 33.4% |
| North Dakota | Milton R. Young | Republican | Re-elected | Milton R. Young (Republican) 63.6%\nQuentin N. Burdick (Democratic) 36.0% |
| Ohio | George H. Bender | Republican | Lost re-election\nDemocratic gain | Frank J. Lausche (Democratic) 52.9%\nGeorge H. Bender (Republican) 47.1% |
| Oklahoma | A. S. Mike Monroney | Democratic | Re-elected | A. S. Mike Monroney (Democratic) 55.4%\nDouglas McKeever (Republican) 44.7% |
| Oregon | Wayne Morse | Democratic | Re-elected | Wayne Morse (Democratic) 54.2%\nDouglas McKay (Republican) 45.8% |
| Pennsylvania | James H. Duff | Republican | Lost re-election\nDemocratic gain | Joseph S. Clark (Democratic) 50.1%\nJames H. Duff (Republican) 49.7% |
| South Carolina | Olin B. Johnston | Democratic | Re-elected | Olin B. Johnston (Democratic) Unopposed |
| South Carolina\nSpecial: Class 2 | Thomas A. Wofford | Democratic | Appointee retired\nWinner elected to finish term ending January 3, 1961\nDemocratic hold | Strom Thurmond (Democratic) Unopposed |
| South Dakota | Francis Case | Republican | Re-elected | Francis Case (Republican) 50.8%\nKenneth Holum (Democratic) 49.2% |
| Utah | Wallace F. Bennett | Republican | Re-elected | Wallace F. Bennett (Republican) 54.0%\nAlonzo F. Hopkin (Democratic) 46.0% |
| Vermont | George D. Aiken | Republican | Re-elected | George D. Aiken (Republican) 66.4%\nBernard G. O'Shea (Democratic) 33.6% |
| Washington | Warren G. Magnuson | Democratic | Re-elected | Warren G. Magnuson (Democratic) 61.1%\nArthur B. Langlie (Republican) 38.9% |
| West Virginia\nSpecial: Class 1 | William R. Laird, III | Democratic | Appointee retired\nWinner elected to finish term ending January 3, 1959\nRepublican gain | Chapman Revercomb (Republican) 53.7%\nWilliam C. Marland (Democratic) 46.3% |
| Wisconsin | Alexander Wiley | Republican | Re-elected | Alexander Wiley (Republican) 58.6%\nHenry W. Maier (Democratic) 41.2% |
Question:
how many states had a democratic gain due to retirement?
Answer:
1