the Leap Year Day falls today (technically because 2012 is a leap year on the Gregorian Calendar). It occurs every 4 years with an exception every 128 years, when we don’t bother with a leap year day. This most closely aligns the annual year with the tropical year (or the calendar year with the observed year).
In four years’ time, we will observe Leap Year 1, the day before the New Year Day between Years 3 and 4.
Another advantage to having the Leap Year at the end of the year (as opposed to the ridiculously disruptive end of the second month as the Gregorian calendar currently does), is that the calendar remains perpetual. Also, as the day lengthens over time, leap seconds can be added to the leap year day.
Chromatic: Year 0 Lunation 0 Day —
Lunar: Year 0 Lunation 0 Day 7
Annual: Year 0 Month — Day LYD