# simple version
DAYS_PER_MONTH = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ]
def ConvertDateToDaysSince2016(date):
    splitted = date.split('/')
    return sum(DAYS_PER_MONTH[1:int(splitted[0])]) + int(splitted[1])

# proper datetime version
import datetime
def ConvertDateToDaysSince2016_UsingDatetime(date):
    splitted = date.split('/')
    return (
        datetime.date(2016, int(splitted[0]), int(splitted[1])) - datetime.date(2016, 1, 1)
    ).days

print(str(ConvertDateToDaysSince2016_UsingDatetime('12/09')))
print(str(ConvertDateToDaysSince2016('12/09')))