Blue moon?

By the way, Senator Smith commented on the so called “Blue Moon” election this year – neither president, senator, nor governor shows up on the ballot this time. I was curious how often this occurred; place mat-doodling suggests it only happens every twelve years, at least here in North Carolina:

2000 – President, Governor
2002 – Senator A
2004 – President, Senator B, Governor
2006 – Blue Moon
2008 – President, Senator A, Governor
2010 – Senator B
2012 – President, Governor
2014 – Senator A
2016 – President, Senator B, Governor
2018 – Blue Moon

For what it's worth, we do have one slight difference from other states -- our state senators are elected every two years, the same as state representatives. There's been a suggestion to change that but I haven't heard much discussion about it.