Regarding the proportion of federal taxes paid by corporations, this table [0] says in 1945, corporations paid 16 billion out of 45 billion, ~36%. But that includes tax revenue sources other than individual income taxes, in 1945 those were 18.3 billion so if you only only count income taxes and corporation taxes, corporations were 47%, pretty close to 50%.
For 2015 (most recent non-estimated year), 344 billion out of 3.2 trillion, about 11%, more than twice the 5% figure. If you again only count income taxes and corporation taxes, income taxes were 1.5 trillion so corporations were 19% of that total.
For 2015 (most recent non-estimated year), 344 billion out of 3.2 trillion, about 11%, more than twice the 5% figure. If you again only count income taxes and corporation taxes, income taxes were 1.5 trillion so corporations were 19% of that total.
[0] http://www.taxpolicycenter.org/statistics/amount-revenue-sou...