CREATE TABLE table_2628 ("District" TEXT, "Vacator" TEXT, "Reason for change" TEXT, "Successor" TEXT, "Date successor seated" TEXT)

Name the reason for change for jonathan jennings
SELECT COUNT("Reason for change") FROM table_2628 WHERE "Successor" = 'Jonathan Jennings'
SELECT COUNT("Reason for change") FROM "table_2628" WHERE "Successor" = 'Jonathan Jennings'