Convention mainly. The calendar in a form as we know it was not introduced until many years after the death of christ. The calculations for that incident were incorrect.
You can purchase a new 2013 calendar in WHSmith shops. You can get a free 2013 calendar by visiting the "Year Planner Calendar" website which has free year planners and calendars for many years.
2002 was the last time the calendar was the same as in 2013.
2015 will be the same calendar as 2009.
The calendar for 2009 was the same as 2015
The 2002 calendar had repeated in years 2013 and 2019 and will next repeat in the year 2030.
2015, 1998, 1987, 1981, 1970, 1959, 1953, 1942, 1931 and 1925 had the same calendar as 2009 and the next year which will have the same calendar as 2009 will be in 2026.
2013
Calendars do actually repeat in a certain pattern. If the year is not a leap year, then the calendar will repeat in 11 years, so a 2009 calendar would again be usable in the year 2020.
No, there was no Canadian GP in the year 2009. The event did not happen because Canada was not part of the F1 racing calendar in the year 2009. However it was back in the calendar in the year 2010.
Either 52 or 53 mondays are there in a calendar year. 2009 has 52 mondays.
1981
52