Question: The JD Power Initial Quality Survey polls more than 50,000 buyers of new motor vehicles 90 days after their purchase. A two-page questionnaire asks about "things gone wrong." Here are data on problems per 100 vehicles for vehicles made by Toyota and by General Motors in recent years. Toyota has been the industry leader in quality. Make two time plots in the same graph to compare Toyota and GM. What are the most important conclusions you can draw from your graphs?

Year 1998 1999 2000 2001 2001 2003 2004
GM 187 179 164 147 130 134 120
Toyota 156 134 116 115 107 115 101