<P> The following are proposed reforms of the Gregorian calendar: </P> <Ul> <Li> Holocene calendar </Li> <Li> International Fixed Calendar (also called the International Perpetual calendar) </Li> <Li> World Calendar </Li> <Li> World Season Calendar </Li> <Li> Leap week calendars <Ul> <Li> Pax Calendar </Li> <Li> Symmetry454 </Li> <Li> Hanke--Henry Permanent Calendar </Li> </Ul> </Li> </Ul> <Li> International Fixed Calendar (also called the International Perpetual calendar) </Li> <Li> World Season Calendar </Li>

When did we start using the current calendar