$20 $40 $60 $80 $100 $120 $140
2011 38 41 47 52 57 63 68
2012 36 40 50 58 68 77 86
2013 43 45 54 63 73 82 90
2014 44 47 55 64 74 83 91
2015 40 45 55 65 75 85 94