The solid black line represents the total snow-covered area, with the most  recent data circled at the end. The grey area shows the interquartile range where 50 percent of the historical data from 2001 to present falls. The dashed line in the middle of the gray area shows the average of the historical data from 2001 to present. The dotted line at the bottom depicts the lowest year on record for snow-covered area; the dotted line at the top depicts the highest year on record for snow-covered area.