The purpose of taxes is to fund the government. The purpose of government is to look after the well-being of its people. That is, the government represents its people to the rest of the world, defends its people against aggressors, and provides infrastructure required to support its people. Taxes should cover the cost of government’s doing what it is required to do. Taxes should be higher when the government provides more services, and lower when it doesn’t. The problem as I see it, is that we do not get enough value for the money we are paying. Also, spending more on the military than is necessary for defense takes money away from more useful programs.
Personally, I think 33% is a good rate. For this money, I would expect that the government would represent our interests to the rest of the world, protect us from foreign attacks (but not to start wars), provide health care to all citizens, and to provide higher education.
There have been several debates over health care and education, so I’ll just touch on them here. Healthy workers are more productive, thus they contribute more money to the economy. Thus, Universal Health Care is good for the country. Similarly, higher education is good for the country because people with higher education tend to make more money, and thus contribute more of it in the form of taxes.
It can be in our interest to give money to foreign nations, and a strong military is important to defend our interests; but how much is too much? How many ballistic missile submarines and super aircraft carriers do we need? Should we continue to prop up various governments, or should we encourage them to stand on their own feet?
Domestically, what about Welfare? I’ve met people who are – I’ll be blunt – lazy. They want the government to give them money for no work. On the other hand, I knew a “welfare mom” with four kids who used her Welfare money to improve her education. She made a career for herself in Aerospace. In my opinion if we were to spend more money on education and health care, fewer people would be content to sit on their butts. (I was out of work for a while, and am still underemployed. But better to be underemployed than to not work at all! I like to think most people would rather work than not.)
So to answer the specific questions in the OP:
[ul][li]33%[/li][li]Services to the People:[/li][list][li]Universal Health Care[/li][li]Subsidies for higher education for any citizen who wants it (to be repaid through National Service or through payroll deductions over, say, 30 years)[/li][li]National defense sufficient to carry out our policies and to support our friends, but not enough to be a bully[/ul][/li]I don’t personally have enough information to decide percentages.[/list]