So why the increase in cloture votes?
Because the minority Republican aggressors demand it. Is it really that difficult to understand? If the minority didn't filibuster, the majority wouldn't have to try and cloture.
When was the highest spike of cloture? Today, with Obama and a Democratic Senate.
When was the second highest? 1993-1995, with Clinton and a Democratic Senate!
When was the third spike? 1987-88, when the Democrats took back the Senate and Bush looked toast in the polls
When did it drop last? Republican takeover beginning in 95, Bush victory in 2001, re-election in 2004-05.
When did it drop the most significantly? Bush in office as the veto power in 1989-92.
The Democratic Party hasn't had a sack since Mike Mansfield was the majority leader.
Because back then the Dems were hard core Great Society/New Deal liberal partisan aggressors and the Republicans were weakwristed Ford/Rockefeller moderates. It's the opposite today.