Please answer a question about the following article about Edmund Burke:

During the year following that contract, with Dodsley, Burke founded the influential Annual Register, a publication in which various authors evaluated the international political events of the previous year. The extent to which Burke contributed to the Annual Register is unclear: in his biography of Burke, Robert Murray quotes the Register as evidence of Burke's opinions, yet Philip Magnus in his biography does not cite it directly as a reference. Burke remained the chief editor of the publication until at least 1789 and there is no evidence that any other writer contributed to it before 1766.

Burke was the chief editor for the Register until at least what year?
1789