Show all opening years and the number of churches that opened in that year.
SELECT open_date ,  count(*) FROM church GROUP BY open_date
SELECT open_date ,  count(*) FROM church GROUP BY open_date
[{'Open_Date': 1830, 'count(*)': 1}, {'Open_Date': 1831, 'count(*)': 1}, {'Open_Date': 1832, 'count(*)': 1}, {'Open_Date': 1836, 'count(*)': 1}, {'Open_Date': 1837, 'count(*)': 1}, {'Open_Date': 1839, 'count(*)': 1}, {'Open_Date': 1840, 'count(*)': 1}, {'Open_Date': 1842, 'count(*)': 1}, {'Open_Date': 1844, 'count(*)': 1}]