The table below lists the number of cellular telephone subscribers (in millions) and subscriber's average local monthly bills for service (in dollars) for the years 1998 through 2008. What type of graph would best describe the data? Year Subscribers (in millions) Average Bill (in dollars) 1998 69.2 39.43 1999 86.0 41.24 2000 190.5 45.27 2001 128.4 47.37 2002 140.8 48.4 2003 158.7 49.91 2004 182.1 50.64 2005 207.9 49.98 2006 233.0 50.56 2007 255.4 49.79 2008 270.3 50.07