St. Louis Rams : biggest year-to-year improvement/decline

Based on regular season win percentage:

                            Change in 
                              win %
Improvement: 1998 -> 1999     0.563   (0.250 -> 0.813)
Decline:     2001 -> 2002    -0.437   (0.875 -> 0.438)
Last Year:   2014 -> 2015     0.063   (0.375 -> 0.438)