Once a month on a Sunday from 3:30-5:30 pm, except for Easter Week (on Good Friday at 11:30).
For 2023, these dates are the 15th January, 19th February, 12th March, 7th April (11:30-1:30), 21st May, 11th June, 16th July, 20th August, 29th October, 19th November, and 17th December.