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:
| District | Incumbent | Party | First elected | Result | Candidates |
| --- | --- | --- | --- | --- | --- |
| Massachusetts 1 | Silvio Conte | Republican | 1958.0 | Re-elected | Silvio Conte (R) Unopposed |
| Massachusetts 2 | Edward Boland | Democratic | 1952.0 | Re-elected | Edward Boland (D) 72.6% Thomas P. Swank (R) 27.4% |
| Massachusetts 3 | Joseph D. Early | Democratic | 1974.0 | Re-elected | Joseph D. Early (D) Unopposed |
| Massachusetts 4 | Barney Frank | Democratic | 1980.0 | Re-elected | Barney Frank (D) 59.5% Margaret Heckler (R) 40.5% |
| Massachusetts 7 | Ed Markey | Democratic | 1976.0 | Re-elected | Ed Markey (D) 77.8% David M. Basile (R) 22.2% |
Question:
what's the first elected with incumbent being joseph d. early
Answer:
1974.0