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:
|  | Name on the Register | Date listed | Location | Municipality |
| --- | --- | --- | --- | --- |
| 1 | Catholic Belltower | November 25, 1980\n(#80004399) | Catholic Mission in Kolonia\n6°58′04″N 158°12′42″E﻿ / ﻿6.967778°N 158.211667°E | Nett |
| 2 | Chief Agriculturist House | September 30, 1976\n(#76002200) | Kolonia\n6°57′31″N 158°12′38″E﻿ / ﻿6.958611°N 158.210694°E | Nett |
| 3 | German Cemetery | September 30, 1976\n(#76002201) | Kolonia\n6°57′07″N 158°12′58″E﻿ / ﻿6.951944°N 158.216111°E | Nett |
| 4 | Japanese Hydro-electric Power Plant | September 30, 1976\n(#76002204) | Kolonia\n6°57′33″N 158°12′24″E﻿ / ﻿6.959167°N 158.206528°E | Nett |
| 5 | Japanese Shrine | September 30, 1976\n(#76002205) | Kolonia\n6°57′50″N 158°12′45″E﻿ / ﻿6.96375°N 158.2125°E | Nett |
| 6 | Japanese Elementary School for Ponapean Children | September 30, 1976\n(#76002203) | Kolonia\n6°58′01″N 158°12′41″E﻿ / ﻿6.966806°N 158.211389°E | Nett |
| 7 | Sokehs Mass Grave Site | September 30, 1976\n(#76002206) | Kolonia\n6°58′10″N 158°12′17″E﻿ / ﻿6.969444°N 158.204861°E | Nett |
| 8 | Spanish Wall | December 19, 1974\n(#74002227) | Litkin Kel\n6°58′05″N 158°13′08″E﻿ / ﻿6.968056°N 158.218889°E | Nett |
| 9 | Japanese Artillery Road and Pohndolap Area | September 30, 1976\n(#76002202) | Sokehs\n6°58′03″N 158°11′00″E﻿ / ﻿6.9675°N 158.183333°E | Sokehs |
| 10 | Nan Madol | December 19, 1974\n(#74002226) | East side of Temwen Island\n6°50′40″N 158°20′09″E﻿ / ﻿6.844444°N 158.335833°E | Madolenihmw |
Question:
how many years are spanned from the earliest listing to the latest listing?
Answer:
6