[USER (data scientist)]: Great! Now, I want to know the win rate percentage for each player. Can you help me calculate that? Please generate the code with the output in series type.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd
import numpy as np
import pickle
from decision_company import read_csv_file, check_elements_in_list, assert_series, logical_and, logical_or, count_unique_values, fill_missing_values, create_dataframe, reset_index

atp_tennis = read_csv_file('atp_tennis.csv')

# YOUR SOLUTION BEGIN:
<code1>
[GENERATE YOUR CODE] 
</code1>
# YOUR SOLUTION END

print(win_rate_percentage)

# save data
pickle.dump(win_rate_percentage,open("./pred_result/win_rate_percentage.pkl","wb"))

---END CODE TEMPLATE---

[YOU (AI assistant)]: Absolutely! We can divide the number of matches won by the number of matches played and multiply by 100. Here's the code:

# MY SOLUTION BEGIN:
