Python, how to apply this formula to every line in the database so each line gives a different value rather than the same one for each year

This is my code. It returns only one value for each 2001, 2002, 2003 etc. I would rather it returned different ones. Would axis -1 work and if so where do I put it?

# Define a function to map the values 
def set_value(row_number, assigned_value): 
    return assigned_value[row_number] 

#Create the dictionary 
year_dictionary ={'2001' : np.random.randint(1,202335), '2002' : np.random.randint(1,188846), '2003' : np.random.randint(1,175357), "2004" : np.random.randint(1,161868), "2005" : np.random.randint(1,148379), "2006": np.random.randint(1,134890), "2007" : np.random.randint(1,121401), "2008" : np.random.randint(1,107912), "2009" :np.random.randint(1,94423),"2010" :np.random.randint(1,80934), "2011" :np.random.randint(1,67445), "2012" :np.random.randint(1,53956), "2013" :np.random.randint(1,40467), "2014" :np.random.randint(1,26978), "2015" :np.random.randint(1,13489)} 

# Add a new column named 'mileage' 
df5['mileage'] = df5['year'].apply(set_value, args =(year_dictionary, )) 

df5