Calculate year-wise total number of runs of Sachin

Calculate year-wise total number of runs of Sachin

OneDayInternational.csv is a csv file containing about 200 records on Sachin’s ODIs from 1990 to 1998. Read this CSV file using DictReader() and calculate year-wise total number of runs of Sachin. Display the same in the following format: 

1990 239
1991 417

…….

Code :-

import csv

reader = csv.DictReader(open('OneDayInternational.csv','r'))
prev_year = -1
run_sum = -1
for row_no, line in enumerate(reader) :
    year = int(line['MatchDate'].split("/")[2])
    runs = int(line['Runs'])
    if year == prev_year:
        run_sum += runs
    else:
        if prev_year == -1 :
            prev_year = year
            run_sum = runs
        else :
            print(str(prev_year) + " " + str(run_sum))
            prev_year = year
            run_sum = runs
print(str(prev_year) + " " + str(run_sum))