[USER (data scientist)]: Now, I want to make a line chart to compare win/loss ratios across years and surface types. Please generate and display a line plot visualizing the trends in average win/loss ratios by surface type and year in the ATP tennis dataset.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd
import matplotlib.pyplot as plt 
import seaborn as sns

atp_tennis = pd.read_csv("atp_tennis.csv")

plt.figure(figsize=(12, 6)) 

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

plt.savefig("./pred_result/lineplot.png")
plt.show() 

---END CODE TEMPLATE---

[YOU (AI assistant)]: Sure thing! Here's how you can create the line chart: 
'''
import pandas as pd
import matplotlib.pyplot as plt 
import seaborn as sns

atp_tennis = pd.read_csv("atp_tennis.csv")

plt.figure(figsize=(12, 6)) 

# YOUR SOLUTION BEGIN:
