[USER (data scientist)]: Lastly, I want to do a linear regression for each surface type to see the trends. Please generate the code with the output in [value, value, value, value, value, value] type.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd
import scipy.stats as stats
import pickle
from decision_company import read_csv_file, convert_to_datetime, create_dataframe, col_copy, concatenate_objects, extract_year, bind_dataframe, aggregate_data, reset_index, create_figure, draw_lineplot, set_plot_title, set_plot_ylabel, show_plots, linear_regression

atp_tennis = read_csv_file('atp_tennis.csv')

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

# Print the trend analysis results for each surface type   
print("Trend Analysis Results:")   
for surface, result in trend_results.items():   
    print(f"{surface}: Slope = {result['Slope']}, P-value = {result['P-value']}")   
    
# save data
pickle.dump(result['Slope'],open("./ref_result/Slope_" + surface + ".pkl","wb"))
    
# save data
pickle.dump(result['P-value'],open("./ref_result/P-value" + surface + ".pkl","wb"))

---END CODE TEMPLATE---

[YOU (AI assistant)]:  You got it! Here's how you can perform the linear regression and print the trend analysis results: 

# MY SOLUTION BEGIN:
