I'm sure that number was much much better before the formation of the Department of Education. Since it's formation, Civics, as it was called back then has taken a back seat to communist doctrine. I graduated High School in 1969; my daughter in 2001. She was taught almost nothing about US History and zero about how the government is supposed to function. My hardest job was to convince her her teacher was wrong.That's awesome!
It scares me that only 3% of high school students can pass.