Both World Wars.
Yes, Singapore has competed in every Summer Olympics, except for 1980, since 1948.
Except for the 1960 Summer Olympics, Jamaica has participated in every Summer Olympics since 1948.
Ethiopia first participated in the Summer Olympics in 1956 and has been to every Summer Olympics, except the 1976 Summer Olympics, since then.
World war one/two im not really sure
The United States participated in the first modern Olympics in Athens in 1896, and since then they have participated in every Olympics except for the 1980 Summer Games in Moscow.
Papua New Guinea has sent a team to every Summer Olympics, except 1980, since 1976. They have not won an Olympic medal.
It was not held during the two world wars.
A census has been conducted every ten years since 1790.
The Summer Olympics have been held every four years since 1896 except for 1916 due to World War I and 1940 and 1944 due to World War II.
Same as the 2008 Olympics, and the 2004 Olympics, and the Olympics before that. and every other 4 years since the Olympics started.
since 1992 except when they missed the 1994 games.
Yes, it's very much in Olympics since 1908; except 1912 and 1924. Women's Field Hockey was included in Olympics in 1980.