Your question needs to be clarified. If we divide "Christians" into (1.) those who are Christian in name only (no personal relationship with Jesus Christ including babies baptized at anothers' request, nice people, church goers, church members, those whose parents are Christians, those who live in America, etc.) and (2.) those who have a personal/living relationship with Jesus Christ after receiving him in prayer as savior from sin and lord (master, boss of their lives). Distinguishing these "Christians" changes the answer, and also may affect your reason for asking the question.
Remember, people have disagreements for three basic reasons: they have different information, have different values or are using different definitions. Always clarify your definitions. Sometimes clarification settles the disagreement. {:-)
*
30
a bunch
54.3%
43%
like 30 to50%
Around about 1 third of High school students but it also depends on the type of school and where it also located.
My guess would be 92%
12.3%
Less than 2%
zero ... magna cum laude is an honor to designate college graduates, not high school
70 %