The National Center for Education Statistics reported the following data on the average cost per year for tuition, fees, and room and board for 4-year public institutions in the United States (nces.ed .gov/fastfacts/display.asp?id=76, retrieved April 17, 2017). Construct a time series plot of these data and comment on the trend over time. 

Year............................Average Cost 

2002............................$14,439 

2003............................$15,505 

2004............................$16,510 

2005............................$17,451 

2006............................$18,471 

2007............................$19,363 

2008............................$20,409 

2009............................$21,126 

2010............................$22,074 

2011............................$23,011 

2012............................$23,872 

2013............................$24,706