If you thought your teen was texting a lot, you’re not crazy. They really are texting a lot. According to a report released today by Nielsen Company, teens send and receive 3,339 texts a month. That’s more than six per every hour they’re awake, an 8 percent jump from last year.

Using recent data from monthly cell phone bills of more than 60,000 mobile subscribers as well as survey data from over 3,000 teens, Nielsen analyzed mobile usage data among teens in the United States for the second quarter of 2010.

Teens aged 13-17, especially teen females, had the busiest thumbs. According to Nielsen, this group sends and receives an average of 4,050 texts per month. Teen males also outpace other male age groups, sending and receiving an average of 2,539 texts. Young adults aged 18-24 come in a distant second, exchanging 1,630 texts per month.

Nielsen says texting, not safety, is the main reason that teens want cell phones. Fully 43 percent of teens claim texting is their primary reason for getting a cell phone, which explains why qwerty input is the first thing they look for in choosing their devices. Safety, which was the main reason for getting a phone in 2008, is now less important. Safety is secondary among girls and less so among boys.

But teens aren’t just texting, they’re also using up a lot more data these days. According to Nielsen, 94 percent of teen subscribers self-identify as advanced data users, turning to their cell phones for messaging, Internet, multimedia, gaming and other activities like downloads.

While teen usage does not reach levels of activity seen by young adults, it has increased substantially versus the second quarter of last year, from 14 MB to 62 MB. This fourfold increase is the largest jump among all age groups. Nielsen says the boost is led by males, who consume 75 MB of data, versus 17 MB in the second quarter of last year. Teen females use about 53 MB of data, compared to 11 MB a year ago.

Teens are also downloading a wider range of applications. Software downloads among teen subscribers who use apps enjoyed a solid 12 percent increase in activity versus last year, from 26 to 38 percent. This includes popular apps such as Facebook, Pandora or YouTube. Usage of the mobile Web also has surpassed activity on pre-installed games, ringtone downloads and instant messaging, too. Other mobile activities like mail and text alerts also saw significant growth.