The Fed since 1990, changed the Fed Funds rate 79 times since 1990. Overall, 47 times were decreases V 32 increases. From 1990 to 2002, Fed Funds was lowered 36 times and increased 14 times for 50 Fed Funds rate changes. From 2003 to present day, Fed Funds was decreased 11 times V 18 increases for a total of 29 changes.
Why demarcate the time periods is because year 2000 under euro introduction in 1999, Central banks adopted meetings in 6 week intervals and a policy holds to current day.
From 1990 to 2002, Fed Funds was decreased 24 times at 25 basis points and 12 times lowered at 50. Increases account for 9 times at 25, 4 times at 50 and 1 at 75.
From 2002 to 2015, increases account for 18 at 25, and 4 decreases at 25, 4 declines at 50. Two reductions were done at 75.
From 1990 to 2002, December was the winning month with 11 Fed Funds rate changes V 9 amendments for November followed by March at 8 and 7 for September and October. July was the least favored month at 3 adjustments.
From 2002 to 2015, December wins again as most popular month with 6 changes, followed by June, January and March at 5 each.
The commonality in Fed changes from 1990 to 2015 is September to December are most popular months while summer months June, July and August are least favored. The noted point is December was changed twice in one month in 1990 and 1991 as well as January 2 times in 2001 and 2008.
Fed funds began August 1954 at 1.22, rose to 12.92 in July 1974 and peaked at 19.10 in June 1981. At current 0.25 and on the 61 year historic floor, the mid point is located at 10.16 to offer context to current rates.
Why the activist Fed and many Fed Funds changes is due to the rise in Repurchase Agreements and changes to Reserve Requirements as both affect not only open market operations by banks and the Fed but borrow and lend rates between banks. The greatest factor to influence Fed funds changes is demand and supply of money and the cost involved.