Why there are more Senate Filibusters now than in the entire history of the country

The easiest way to determine how many filibusters have taken place is to see how many cloture votes have been taken.  A cloture vote is a vote to end debate and thus kill the filibuster.  The chart, from the U.S. Senate Historical Office,  illustrates all the cloture votes taken since 1917 when the rule allowing for cloture was adopted.  Of the 946 cloture votes taken since 1917, 95% (899 votes) occurred since 1971!

The reason for this increase appears to be a change in Senate Rule XXII in 1975.  Prior to that change it took 2/3's of the Senators present and voting  to invoke cloture.  After the rule change it took 3/5's of those Senators duly chosen and sworn to invoke cloture, i.e, 3/5s of the total Senate whether the Senators were on the floor to vote or not.  That rule change changed the whole dynamic of filibusters.  Prior to the rule change the onus was on those who supported a filibuster to ensure that there were sufficient Senators available at all times to come to the Senate floor to prevent a successful cloture vote.  After the rule change, the onus was on those who supported cloture to come up with 60 votes.  No longer did the proponents of a filibuster have to work to be ready to repel a cloture vote at any given moment.  Now it was a simple matter of whether those who wanted to end debate had 60 votes or not. 

Admittedly cloture votes increased in the four years prior to the Rule XXII change.  However, most of the filibusters in 1971-1972 involved civil rights bills or amendments to change cloture rules. (10 of 20).  These are bills that historically resulted in filibusters.  The increase in  filibusters in 1973-1974 are harder to explain.   

This suggests that if one wants to end what has become the need for 60 vote Senate majorities to pass legislation, Senate Rule XXII should be amended to allow cloture when passed by a 3/5's majority of the members present and voting rather than 3/5's of Senators duly chosen and sworn.  This puts the onus back on those wanting to filibuster to ensure that they have sufficient members available at any given time to ensure that there is not a 3/5's majority for cloture.  This would once again turn the filibuster into a physical test of just how serious the filbusters are in talking a bill to death and turn away from just being a test of ideology.