2006: March, June, September, December

2007: March, June, September, December

2008: March, June, September, December

2009: February, June, October

2010: February, June, October

2011: February, June, October

2012: February, June, October

2013: February, June, October

2014: February, June, October

2015: February, June, October

2016: February, June, October

2017: February, June, October

2018: February, June