Supreme Court Approval: It's All Partisan, Baby

Andrew Prokop draws my attention this morning to a Gallup chart of Supreme Court approval ratings that I've never seen before. It shows approval by political affiliation, and it's kind of interesting. Here it is with my annotations:

There are five big spikes over the past 15 years, and three of them have obvious causes. In 2001 Republican approval spiked after the Bush v. Gore decision; in 2012 Democratic approval spiked after the court upheld Obamacare; and in 2014 Republican approval spiked after the Hobby Lobby decision. But what happened in 2005 and 2009?

In 2005-06, Republican approval spiked but Democratic approval was stable. Was this because of Bush's re-election or because Roberts and Alito were named to the court? Or both? But if that were the case, shouldn't Democratic approval have gone down?

And in 2009, Democratic approval spiked. Was this because of Obama's election or because Sotomayor was named to the court? Or both?

I'm not sure. If these two spikes were due to presidents being elected, what happened in 2013? Why no spike? And if it's due to justices being nominated, why no Democratic love for Elena Kagan in 2010? Or is there something else going on? I can't think of any big Supreme Court decisions that could account for the 2005 and 2009 spikes. What other possibilities are there?