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 | Vacator | Reason for change | Successor | Date successor seated |
| --- | --- | --- | --- | --- |
| Pennsylvania 18th | Robert J. Corbett (R) | Died April 25, 1971 | H. John Heinz III (R) | November 2, 1971 |
| Kentucky 6th | John C. Watts (D) | Died September 24, 1971 | William P. Curlin, Jr. (D) | December 4, 1971 |
| Pennsylvania 27th | James G. Fulton (R) | Died October 6, 1971 | William S. Conover (R) | April 25, 1972 |
| Alabama 3rd | George W. Andrews (D) | Died December 25, 1971 | Elizabeth B. Andrews (D) | April 4, 1972 |
| New York 20th | William Fitts Ryan (D) | Died September 17, 1972. | Vacant | Not filled this congress |
| Ohio 16th | Frank T. Bow (R) | Died November 13, 1972. | Vacant | Not filled this congress |
Question:
How many successors were seated in the New York 20th district?
Answer:
1.0