only two countries, plus the European Space Agency, that have achieved Mars orbit (by launch year):

1. United States 1964
2. United States 1969
3. Soviet Union 1973
4. United States 1975
5. United States 1996
6. ESA 2003
7. United States 2003
8. United States 2005
9. United States 2007
10. United States 2011

And there are only two countries that have successfully landed on Mars (by landing year):

1. Soviet Union 1971
2. United States 1976
3. United States 1997
4. United States 2003
5. United States 2008
6. United States 2012

Japan launched a probe, but it failed to achieve orbit (it "missed the planet") and China had a joint venture with Russia that never left Earth's orbit. Wikipedia has a nice graphic [wikimedia.org] illustrating the history of Mars exploration.