For American black people in the past decade(s), violent crime is down and educational attainment is up. The trends are even better for young black people, presumably the people who would be most swayed by the content in hip-hop songs. Teen pregnancy and juvenile violence/arrests are down and continuing to fall. Less kids are dropping out of high school, and more are going to college and graduating. If hip-hop is damaging black people, the effect is so subtle that it doesn't actually show up in any statistics. That is to say, the effect is so subtle that there's no evidence that it even exists.

Also, the ten year cut-off is arbitrary. It's not like hip-hop has gotten appreciably more violent or ignorant in the past 10 years. If you really want to make the case that violent/ignorant has a negative affect on black people, you should be able to show that affect dating back to when violent/ignorant hip-hop became a major part of black culture, which I would say is at least 20-25 years ago. Interestingly, the inflection point for a lot of the negative trends for black people - particularly violent crime and juvenile delinquency - seems to come around 20-25 years ago. If we were as simple as a Fox News commentator, we might see that and conclude that hip-hop is responsible for this turnaround. But we're smarter than that, and know that these are complex problems with origins that run deeper than the lyrics of a simple rap song.

Some references:
http://www.ojjdp.gov/ojstatbb/crime/JAR_Display.asp?ID=qa05261
http://tinyurl.com/br5nlcs
http://www.childtrends.org/wp-content/uploads/2012/10/01_Fig1.jpg
http://www.pewresearch.org/files/2014/04/FT_14.04.23_collegeRace_enrollTrend-640-2.png
http://www.census.gov/hhes/socdemo/education/data/cps/historical/fig8.jpg