how to count element inside lists of a dictionary in python?

Let’s say I have a dictionary like this:

allName = {
          'name1': ['sainz', 'gasly'], 
          'name2': ['sainz', 'gasly', 'stroll'],
          'name3': ['sainz', 'gasly', 'stroll']
}

How can I know that there are 3 sainz names, 3 ‘gasly’ names, 2 ‘stroll’ names inside the dictionary?

I want to print it out like this:

sainz: 3
gasly: 3
stroll: 2

Thanks before hand!

Answer

the easiest way would probably collections counter plus itertools.chain

import itertools    
import collections
print(collections.Counter(itertools.chain(*data.values()))  

I think would work