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:
| Institution | Location | Nickname | Founded | Founding Religious Affiliation | Enrollment | Joined |
| --- | --- | --- | --- | --- | --- | --- |
| Amherst College | Amherst, Massachusetts | Lord Jeffs | 1821.0 | Congregationalist | 1817.0 | 1971.0 |
| Bates College | Lewiston, Maine | Bobcats | 1855.0 | Free Will Baptist | 1769.0 | 1971.0 |
| Bowdoin College | Brunswick, Maine | Polar Bears | 1794.0 | Congregationalist | 1777.0 | 1971.0 |
| Colby College | Waterville, Maine | White Mules | 1813.0 | Northern Baptist | 1838.0 | 1971.0 |
| Connecticut College | New London, Connecticut | Camels | 1911.0 | Methodist | 1911.0 | 1982.0 |
| Hamilton College | Clinton, New York | Continentals | 1793.0 | Presbyterian | 1864.0 | 1971.0 |
| Middlebury College | Middlebury, Vermont | Panthers | 1800.0 | Congregationalist | 2507.0 | 1971.0 |
| Trinity College | Hartford, Connecticut | Bantams | 1823.0 | Episcopalian | 2344.0 | 1971.0 |
| Tufts University | Medford, Massachusetts | Jumbos | 1852.0 | Universalist | 5138.0 | 1971.0 |
| Wesleyan University | Middletown, Connecticut | Cardinals | 1831.0 | Methodist | 2870.0 | 1971.0 |
Question:
When did the institution located in Lewiston, Maine join the conference? 
Answer:
1971.0