Why was the Nobel Prize in literature not awarded between 1940 and 1943?

Nobel Prizes in Literature have been awarded since 1901. It was not awarded on seven occasions: in 1914, 1918, 1935, 1940, 1941, 1942, and 1943.

Why were the Literature Prizes not awarded in those years? In the statutes of the Nobel Foundation it says: "If none of the works under consideration is found to be of the importance indicated in the first paragraph, the prize money shall be reserved until the following year. If, even then, the prize cannot be awarded, the amount shall be added to the Foundation's restricted funds." During World War I and II, fewer Nobel Prizes were awarded.