How much money is spent on space exploration?
Space agencies involved in human space flight are located in the US (NASA), Russia, The European Union (ESA), China, Canada, Japan and India. The US, Russia and China are the only countries to have independently put people in space. India and Japan state that they have the intention of doing this in the coming decades. European and Canadian astronauts fly with NASA, and the Russian Space Agency and are involved in the International Space Station.
You can see the NASA budget over the last 40 or so years here. In 2005 NASA had a budget of $16.2 billion, this includes not only the human spaceflight division, but also other engineering projects, and science funded by NASA. The total federal spending budget in 2005 was on the order of $2 trillion ($2000 billion), making the NASA share 0.8% of the budget. By comparison roughly 19% of the budget was spent on the Military, 21% on Social Security and 8% went to paying interest on the national debt.
The ESA budget for 2005 was 2.98 billion euros (about 3.5 billion dollars), but many European countries also have their own space agencies which are independently funded, so it’s not strictly a fair comparison.
ESA and NASA are by far the highest funded agencies. The Russian space agency has an annual budget of $800-900 million dollars (and it’s about the same for India), Japan ~1.8 billion, China ~1.2 billion.