Era
1945-
14
1991-
13
20th century
10
1917-
8
1945-1990
8
1951-
6
1821-1945
5
1918-1938
5
1938-1945
5
1945-1992
5
1989-
5
1898-1935
4
1918-1945
4
1945-1980
4
19th century
4
Civil War, 1861-1865
4
Since 1991
4
1904-1995
3
1910-1945
3
1940-1945
3
1945-1989
3
1970-1981
3
1975-
3
German occupation, 1940-1945
3
Revolution, 1789-1799
3
To 1517
3
To 1968
3
1796-1918
2
1824-1920
2
1830-1875
2
1848-1918
2
1860-1910
2
1861-1865
2
1864-1910
2
1867-
2
1875-1904
2
1895-
2
1898 - 1935
2
1900-1999
2
1917-1936
2
1931-1939
2
1939-1945
2
1939-1975
2
1945 - 1990
2
1945-1922
2
1948-
2
1948-1994
2
1960-
2
1967-1995
2
1970-
2
more ...