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:
| School | Location | Mascot | County | Enrollment | IHSAA Class | Year Joined | Previous Conference |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Borden * | Borden | Braves | 228.0 | A | 10 Clark | 1974.0 | Lost River |
| Crothersville * | Crothersville | Tigers | 180.0 | A | 36 Jackson | 1974.0 | Mid-Hoosier |
| Henryville | Henryville | Hornets | 347.0 | AA | 10 Clark | 1977.0 | Lost River |
| Lanesville | Lanesville | Eagles | 237.0 | A | 31 Harrison | 1979.0 | Blue River |
| New Washington | New Washington | Mustangs | 273.0 | A | 10 Clark | 1974.0 | Dixie-Monon |
| South Central (Elizabeth) | Elizabeth | Rebels | 277.0 | A | 31 Harrison | 1979.0 | Blue River |
Question:
What is the average year joined of the 277 county?
Answer:
1979.0