How to end this loop if the user enters 'end'?

I have to find how many characters are in each individual string a user inputs and then total amount of characters from all the inputs, ending the loop when the user enters 'end'.

For some reason my loop won't break, I've tried a different things but nothings working for me. I feel like it's probably something really simple that I'm forgetting, any help would be great!

upper_total = 0
lower_total = 0
alpha_total = 0
num_total = 0
white_total = 0
while True:
    user_string = input("Enter a string: ")
    for entry in user_string:
        if entry == 'end':
            break
        if entry.isupper():
            upper_total += 1
        if entry.islower():
            lower_total += 1
        if entry.isalpha():
            alpha_total += 1
        if entry.isdigit():
            num_total += 1
        if entry.isspace():
            white_total += 1
    print("Capital Letters: ", sum(1 for entry in user_string if entry.isupper()))
    print("Lowercase Letters: ", sum(1 for entry in user_string if entry.islower()))
    print("Letters: ", sum(1 for entry in user_string if entry.isalpha()))
    print("Numbers: ", sum(1 for entry in user_string if entry.isdigit()))
    print("White space: ", sum(1 for entry in user_string if entry.isspace()))
    print('Upper total: ', upper_total)
    print('lower total: ', lower_total)
    print('alpha total: ', alpha_total)
    print('num total: ', num_total)
    print('white space total: ', white_total)