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 | Founded | Type | Enrollment | Nickname | Joined | Left | Football Conference | Primary Conference |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Boston State College | Boston, Massachusetts | 1872.0 | Public | N/A | Beacons | 1972 | 1982 | Merged into the University of Massachusetts Boston | Merged into the University of Massachusetts Boston |
| Bridgewater State University | Bridgewater, Massachusetts | 1840.0 | Public | 12,127 | Bears | 1965 | 2013 | MASCAC | MASCAC |
| Fitchburg State University | Fitchburg, Massachusetts | 1894.0 | Public | 5,201 | Falcons | 1985 | 2013 | MASCAC | MASCAC |
| Framingham State University | Framingham, Massachusetts | 1839.0 | Public | 5,989 | Rams | 1973 | 2013 | MASCAC | MASCAC |
| University of Massachusetts Boston | South Boston, Massachusetts | 1964.0 | Public | 15,741 | Beacons | 1988 | 2001 | no longer sponsors football | Little East (LEC) |
| University of Massachusetts Dartmouth | Dartmouth, Massachusetts | 1895.0 | Public | 7,451 | Corsairs | 1988 | 2013 | Little East (LEC) | Little East (LEC) |
| Massachusetts Maritime Academy | Buzzards Bay, Massachusetts | 1891.0 | Public | 1,130 | Buccaneers | 1972 | 2013 | MASCAC | MASCAC |
| New England College | Henniker, New Hampshire | 1946.0 | Private | 1,460 | Pilgrims | 1971 | 1973 | no longer sponsors football | NAC |
| University of New Haven | West Haven, Connecticut | 1920.0 | Private | 6,000 | Chargers | 1973 | 1982 | Northeast-10 | Northeast-10 |
| Plymouth State University | Plymouth, New Hampshire | 1871.0 | Public | 6,600 | Panthers | 1971 1989 | 1991 2013 | MASCAC | Little East (LEC) |
| Western Connecticut State University | Danbury, Connecticut | 1903.0 | Public | 6,001 | Colonials | 1979 | 1986 | MASCAC | Little East (LEC) |
| Westfield State University | Westfield, Massachusetts | 1838.0 | Public | 5,166 | Owls | 1982 | 2013 | MASCAC | MASCAC |
Question:
What date did the institution that left in 2013 and that is nicknamed Corsairs, join? 
Answer:
1988.0