import json

ref = {1: 'Jan', 2: 'Feb', 3: 'Mar', 4: 'Apr', 5: 'May', 6: 'June', 7: 'July', 8: 'Aug', 9: 'Sept', 10: 'Oct', 11: 'Nov', 12: 'Dec'}

birthdays = json.load(open('birthdays.json'))
months_dict = {}

for date in birthdays.values():
    items = date.split('/')
    month_n = int(items[1])
    name= ref[month_n]
    if name in months_dict.keys():
        months_dict[name] = months_dict[name] + 1
    else:
        months_dict[name] = 1
print(months_dict)