Time series for Motor Vehicle Deaths. The following values are numbers of motor vehicle deaths in the United States for years beginning with 1980. The data are arranged in order by row. Construct a time-series graph and then determine whether there appears to be a trend. If so, provide a possible explanation.

51,091 49,301 43,945 42,589 44,257 43,825 46,087 46,390 47,087 45,582 44,599 41,508 39,250 40,150 40,716 41,817 42,065 42,013 41,501 41,717 41,945 42,196 43,005 42,884 42,836 43,443 42,642 41,059 37,261 33,808 32,708