def getdata(year):
    df = pd.read_csv('data/CTA_-_Ridership_-_Bus_Routes_-_Monthly_Day-Type_Averages___Totals.csv')
    df = df[['route', 'routename', 'Month_Beginning', 'Avg_Weekday_Rides', 'Avg_Saturday_Rides', 'Avg_Sunday-Holiday_Rides', 'MonthTotal']]
    df['year'] = pd.DatetimeIndex(df['Month_Beginning']).year

    if year >= 2001 and year <= 2015:
        df = df[df['year'] == int(year)]  # get data base on the given year in the argument
        df['month'] = pd.DatetimeIndex(df['Month_Beginning']).month
    else:
        df = df[df['year'] <= 2015]  # get data base on the given year in the argument

    df.set_index(['route', 'routename'], inplace=True)
    return df

# inyear = 2014 # Enter year here (from 2001 to 2015)
# from cta_data import getdata
df_ridership = getdata(2014)
df_ridership.head()