Python random number to values columns

I have a large dataset with the columns 'group' and 'postcode'. An example of the df is given below:

Age   
65+ 
16-25
16-25 
26-39 
40-64 
65+ 
26-39 
40-64 
16-25 
65+

I am trying to affect to each row value a random value with the code below

df['AGE'] = df['AGE'].replace({'65+': randint(65,100), '16-25': randint(16,25), '26-39': randint(26,39), '40-64': randint(40,64) })

But what I'm getting are four random values to each of these values: {'65+', '16-25', '26-39', '40-64'} like so :

Age   
73 
23
23 
34 
42 
73 
34 
42 
23 
73

Can someone please help me figure out what am I doing wrong by correcting my code?