There's a ceremony every year, and therefore it'll be the 80th Oscar. You can do the counting: 1929, 1930, 1931, 1932, 1933, 1934, 1935, 1936, 1937, 1938 - These are the first ten. As you can see, the 10th was in 1938. You can keep counting, and see that the 20th was in 1948, the 30th in 1958, the ...