[USER (data scientist)]: Great! Now, let's group the DataFrame by year and surface type, and find the average win/loss ratio. Please generate a DataFrame summarizing the average win/loss ratio by year and surface type in the ATP tennis dataset.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd
import pickle
from decision_company import read_csv_file,

# please import the necessary private functions from decision_company first

atp_tennis = read_csv_file('atp_tennis.csv')

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

print(yearly_surface_data)

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

---END CODE TEMPLATE---

[YOU (AI assistant)]: You got it! Here's how you can do that: 
'''
import pandas as pd
import pickle
from decision_company import read_csv_file,

# please import the necessary private functions from decision_company first

atp_tennis = read_csv_file('atp_tennis.csv')

# YOUR SOLUTION BEGIN:
