| Year | Drought levels | ||||
| MI | Lessly drought | Significantly drought | Severely drought | Extremely drought | |
| 1986 | 0.50 | 0 | 0 | 1 | 0 |
| 1987 | 0.41 | 0 | 0 | 1 | 0 |
| 1988 | 0.38 | 0 | 0 | 0 | 1 |
| 1989 | 0.45 | 0 | 0 | 1 | 0 |
| 1990 | 0.42 | 0 | 0 | 1 | 0 |
| 1991 | 0.43 | 0 | 0 | 1 | 0 |
| 1992 | 0.52 | 0 | 0 | 1 | 0 |
| 1993 | 0.64 | 0 | 0 | 1 | 0 |
| 1994 | 0.48 | 0 | 0 | 1 | 0 |
| 1995 | 0.54 | 0 | 0 | 1 | 0 |
| 1996 | 0.83 | 0 | 1 | 0 | 0 |
| 1997 | 0.51 | 0 | 0 | 1 | 0 |
| 1998 | 1.10 | 0 | 1 | 0 | 0 |
| 1999 | 0.78 | 0 | 0 | 1 | 0 |
| 2000 | 1.02 | 0 | 1 | 0 | 0 |
| 2001 | 0.56 | 0 | 0 | 1 | 0 |
| 2002 | 0.53 | 0 | 0 | 1 | 0 |
| 2003 | 0.64 | 0 | 0 | 1 | 0 |
| 2004 | 0.43 | 0 | 0 | 1 | 0 |
| 2005 | 0.74 | 0 | 0 | 1 | 0 |
| 2006 | 0.52 | 0 | 0 | 1 | 0 |
| 2007 | 0.83 | 0 | 1 | 0 | 0 |
| 2008 | 1.09 | 0 | 1 | 0 | 0 |
| 2009 | 0.80 | 0 | 0 | 1 | 0 |
| 2010 | 0.96 | 0 | 1 | 0 | 0 |
| 2011 | 0.71 | 0 | 0 | 1 | 0 |
| 2012 | 0.78 | 0 | 0 | 1 | 0 |
| 2013 | 0.80 | 0 | 0 | 1 | 0 |
| 2014 | 0.47 | 0 | 0 | 1 | 0 |
| 2015 | 0.55 | 0 | 0 | 1 | 0 |
| 2016 | 1.00 | 0 | 1 | 0 | 0 |
| Total | 0 | 7 | 23 | 1 | |
| Frequency | 0 | 23 | 74 | 3 | |
| Average: 0.66 | |||||