Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
List of ambassadors of the United States to Mexico
Table title:
List of ambassadors
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Ambassador </th><th colspan=1 rowspan=1 > Presentation </th><th colspan=1 rowspan=1 > Termination </th><th colspan=1 rowspan=1 > Appointed by </th></tr>
<tr> <td colspan=1 rowspan=1 > Powell Clayton </td><td colspan=1 rowspan=1 > January 3, 1899 </td><td colspan=1 rowspan=1 > May 26, 1905 </td><td colspan=1 rowspan=1 > William McKinley </td></tr>
<tr> <td colspan=1 rowspan=1 > Edwin H. Conger </td><td colspan=1 rowspan=1 > June 15, 1905 </td><td colspan=1 rowspan=1 > August 3, 1905 </td><td colspan=1 rowspan=2 > Theodore Roosevelt </td></tr>
<tr> <td colspan=1 rowspan=1 > David Eugene Thompson </td><td colspan=1 rowspan=1 > March 8, 1906 </td><td colspan=1 rowspan=1 > December 1, 1909 </td></tr>
<tr> <td colspan=1 rowspan=1 > Henry Lane Wilson </td><td colspan=1 rowspan=1 > March 5, 1910 </td><td colspan=1 rowspan=1 > February 18, 1913 </td><td colspan=1 rowspan=1 > William Howard Taft </td></tr>
<tr> <td colspan=1 rowspan=1 > Henry P. Fletcher </td><td colspan=1 rowspan=1 > March 3, 1917 </td><td colspan=1 rowspan=1 > January 25, 1919 </td><td colspan=1 rowspan=1 > Woodrow Wilson </td></tr>
<tr> <td colspan=1 rowspan=1 > Charles B. Warren </td><td colspan=1 rowspan=1 > March 31, 1924 </td><td colspan=1 rowspan=1 > July 22, 1924 </td><td colspan=1 rowspan=3 > Calvin Coolidge </td></tr>
<tr> <td colspan=1 rowspan=1 > James R. Sheffield </td><td colspan=1 rowspan=1 > October 15, 1924 </td><td colspan=1 rowspan=1 > June 5, 1927 </td></tr>
<tr> <td colspan=1 rowspan=1 > Dwight Morrow </td><td colspan=1 rowspan=1 > October 29, 1927 </td><td colspan=1 rowspan=1 > September 17, 1930 </td></tr>
<tr> <td colspan=1 rowspan=1 > J. Reuben Clark </td><td colspan=1 rowspan=1 > November 28, 1930 </td><td colspan=1 rowspan=1 > February 14, 1933 </td><td colspan=1 rowspan=1 > Herbert Hoover </td></tr>
<tr> <td colspan=1 rowspan=1 > Josephus Daniels </td><td colspan=1 rowspan=1 > April 24, 1933 </td><td colspan=1 rowspan=1 > November 9, 1941 </td><td colspan=1 rowspan=2 > Franklin D. Roosevelt </td></tr>
<tr> <td colspan=1 rowspan=1 > George S. Messersmith </td><td colspan=1 rowspan=1 > February 24, 1942 </td><td colspan=1 rowspan=1 > May 15, 1946 </td></tr>
<tr> <td colspan=1 rowspan=1 > Walter C. Thurston </td><td colspan=1 rowspan=1 > June 17, 1946 </td><td colspan=1 rowspan=1 > November 4, 1950 </td><td colspan=1 rowspan=2 > Harry S. Truman </td></tr>
<tr> <td colspan=1 rowspan=1 > William O'Dwyer </td><td colspan=1 rowspan=1 > November 23, 1950 </td><td colspan=1 rowspan=1 > December 6, 1952 </td></tr>
<tr> <td colspan=1 rowspan=1 > Francis White </td><td colspan=1 rowspan=1 > April 28, 1953 </td><td colspan=1 rowspan=1 > June 30, 1957 </td><td colspan=1 rowspan=2 > Dwight D. Eisenhower </td></tr>
<tr> <td colspan=1 rowspan=1 > Robert C. Hill </td><td colspan=1 rowspan=1 > July 25, 1957 </td><td colspan=1 rowspan=1 > December 1, 1960 </td></tr>
<tr> <td colspan=1 rowspan=1 > Thomas C. Mann </td><td colspan=1 rowspan=1 > May 8, 1961 </td><td colspan=1 rowspan=1 > December 22, 1963 </td><td colspan=1 rowspan=1 > John F. Kennedy </td></tr>
<tr> <td colspan=1 rowspan=1 > Fulton Freeman </td><td colspan=1 rowspan=1 > April 6, 1964 </td><td colspan=1 rowspan=1 > January 6, 1969 </td><td colspan=1 rowspan=1 > Lyndon B. Johnson </td></tr>
<tr> <td colspan=1 rowspan=1 > Robert H. McBride </td><td colspan=1 rowspan=1 > July 22, 1969 </td><td colspan=1 rowspan=1 > January 25, 1974 </td><td colspan=1 rowspan=2 > Richard Nixon </td></tr>
<tr> <td colspan=1 rowspan=1 > Joseph J. Jova </td><td colspan=1 rowspan=1 > January 30, 1974 </td><td colspan=1 rowspan=1 > February 21, 1977 </td></tr>
<tr> <td colspan=1 rowspan=1 > Patrick Joseph Lucey </td><td colspan=1 rowspan=1 > July 19, 1977 </td><td colspan=1 rowspan=1 > October 31, 1979 </td><td class="highlighted"  colspan=1 rowspan=2 > Jimmy Carter </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Julian Nava </td><td class="highlighted"  colspan=1 rowspan=1 > May 7, 1980 </td><td colspan=1 rowspan=1 > April 3, 1981 </td></tr>
<tr> <td colspan=1 rowspan=1 > John Gavin </td><td colspan=1 rowspan=1 > June 5, 1981 </td><td colspan=1 rowspan=1 > June 10, 1986 </td><td colspan=1 rowspan=2 > Ronald Reagan </td></tr>
<tr> <td colspan=1 rowspan=1 > Charles J. Pilliod Jr. </td><td colspan=1 rowspan=1 > November 4, 1986 </td><td colspan=1 rowspan=1 > April 7, 1989 </td></tr>
<tr> <td colspan=1 rowspan=1 > John Negroponte </td><td colspan=1 rowspan=1 > July 3, 1989 </td><td colspan=1 rowspan=1 > September 5, 1993 </td><td colspan=1 rowspan=1 > George H. W. Bush </td></tr>
<tr> <td colspan=1 rowspan=1 > James R. Jones </td><td colspan=1 rowspan=1 > September 10, 1993 </td><td colspan=1 rowspan=1 > June 25, 1997 </td><td colspan=1 rowspan=2 > Bill Clinton </td></tr>
<tr> <td colspan=1 rowspan=1 > Jeffrey Davidow </td><td colspan=1 rowspan=1 > August 5, 1998 </td><td colspan=1 rowspan=1 > September 14, 2002 </td></tr>
<tr> <td colspan=1 rowspan=1 > Tony Garza </td><td colspan=1 rowspan=1 > November 22, 2002 </td><td colspan=1 rowspan=1 > January 20, 2009 </td><td colspan=1 rowspan=1 > George W. Bush </td></tr>
<tr> <td colspan=1 rowspan=1 > Carlos Pascual </td><td colspan=1 rowspan=1 > August 9, 2009 </td><td colspan=1 rowspan=1 > March 19, 2011 </td><td colspan=1 rowspan=3 > Barack Obama </td></tr>
<tr> <td colspan=1 rowspan=1 > Earl Anthony Wayne </td><td colspan=1 rowspan=1 > August 2, 2011 </td><td colspan=1 rowspan=1 > July 31, 2015 </td></tr>
<tr> <td colspan=1 rowspan=1 > Roberta S. Jacobson </td><td colspan=1 rowspan=1 > June 20, 2016 </td><td colspan=1 rowspan=1 > May 5, 2018 </td></tr>
<tr> <td colspan=1 rowspan=1 > William H. Duncan </td><td colspan=1 rowspan=1 > 2018 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Donald Trump </td></tr>
</table>
Question:
Who appointed Julian Nava as a U.S. Ambassador to Mexico, and what year was he appointed?
Answer:
In 1980, Julian Nava was appointed U.S. Ambassador to Mexico by President Jimmy Carter.