This post has been edited because I just realised the Excel spreadsheet I used to work out the luckiness factors had a mistake in it!
It's true, we are now in what I like to call an Unlucky Year. Let me explain. The weirdness of the calendar means that every year has either one, two or three instances of a Friday The Thirteenth, and this year is one of the ones with three. 2006 and 2007 were Average Years (two Friday 13ths), but if we manage to get through the misfortunes of 2009, the following two years will be Lucky Years (just one Friday 13th)!
Unlucky Years don't happen very often. As any calendar-calculator knows, the days of the week run in 28-year sequences - if you were born on a Thursday, your 28th birthday will also be on a Thursday. If your third birthday is on a Saturday, your 31st birthday will be on a Saturday too. And, as a side note, during any 28-year cycle, each date will land on each day of the week exactly four times. So if you're one of those people who complain that your birthday is never on a weekend, you're lying.
In every 28-year cycle, there are 12 Lucky Years, 12 Average Years and just four Unlucky Years. The last Unlucky Year was 1998, the next will be 2012 (then 2015, then not until 2026). At one extremely boring point in the 28-year cycle, there are four consecutive Average Years - the next one is the dull period from 2017 to 2020 inclusive. The best run of luck you ever get is two Lucky Years in a row.
The three thirteenths to watch out for this year will be in February, March and November, as is the case in three of the four Unlucky Years of the cycle. The other is an Unlucky Leap Year, and has Friday 13ths in January, April and July.
Speaking of leap years, the year 2100 will not be a leap year, which will throw the 28-year sequence out. The upshot of this is that there will be some 28-year periods overlapping the turn of the century which have five or even six Unlucky Years in them! I'm going to spend the entire period from 2078 to 2099 hiding under my bed!
I hope you've enjoyed this fascinating blog entry. If you didn't, make sure to avoid this blog on July 6th, when I and all Excel users around the world will be celebrating Day 40000!