List the number of vacators when successors were formally installed on June 22, 1868.
CREATE TABLE table_26650 (
    "State (class)" text,
    "Vacator" text,
    "Reason for change" text,
    "Successor" text,
    "Date of successors formal installation" text
)
SELECT COUNT("Vacator") FROM table_26650 WHERE "Date of successors formal installation" = 'June 22, 1868'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: List the number of vacators when successors were formally installed on June 22, 1868. ### Input: CREATE TABLE table_26650 (
    "State (class)" text,
    "Vacator" text,
    "Reason for change" text,
    "Successor" text,
    "Date of successors formal installation" text
) ### Response: SELECT COUNT("Vacator") FROM table_26650 WHERE "Date of successors formal installation" = 'June 22, 1868'