It will happen one year in 7 on average depending how the Leap Years fall. After this year the next one is in 2023, 6 years hence. Roger On 25/07/2017 20:51, Ann Markle wrote: > ps. It also happens in 2028, so it must be every 11 years. Strange. > > Ann > > The Rev. Ann Markle > Buffalo, NY > ann.markle at aya.yale.edu >