graphic ages and calculate min max mean

import matplotlib.pyplot as plot
from random import randint

#count amount of people with certain ages
#1 for >1 and <19
#2 for >18 and <41
#3 for >40 and <61
#4 for > 60
def count_function(lista,item):
    item_num=0
    if item == 0:
        for list_item in lista: #search ages between 1 and 18 years and return amount of people
            if list_item > 0 and list_item < 19:
                item_num += 1
        return item_num
    elif item == 1:
        for list_item in lista: #search ages between 19 and 40 years and return amount of people
            if list_item > 18 and list_item < 41:
                item_num += 1
        return item_num
    elif item == 2:
        for list_item in lista: #search ages between 41 and 60 years and return amount of people
            if list_item > 40 and list_item < 61:
                item_num += 1
        return item_num
    elif item == 3:
        for list_item in lista: #search ages older than 60 years and return amount of people
            if list_item > 60:
                item_num += 1
        return item_num
    else:
        print("Error")

#create a list of random ages for 30 people
def create_ages_list():
    ages_list = []
    for x in range (0, 30):
        ages_list.append(randint(1, 80))    # Generate a random number from 0 to 80 and append to list of ages
    #print()
    return ages_list

#create the distribution list of ages acording to the list
#>1 and <19
#>18 and <41
#>40 and <61
#> 60
def create_age_dist_list(ages_dist_list):
    count=0
    list_p=[]
    for item in range(0,4):
        list_p.append(count_function(ages_dist_list,count))
        count += 1

    return list_p

def graphic_ages(range_ages,ages_dist_list):
    plot.bar(range_ages, ages_dist_list, align='center', alpha=0.5)

    plot.xticks(range_ages)
    plot.ylabel('Age range frequency')
    plot.xlabel('Age range')
    plot.title('Age Ranges')

    plot.show()
    #plot.savefig(fname="Quiz Chart.png")

def calculate_max_age(ages_list):
    max_age=0
    for item in ages_list:
        if item > max_age:
            max_age=item
    return max_age

def calculate_min_age(ages_list):
    min_age=100
    for item in ages_list:
        if item < min_age:
            min_age=item
    return min_age

def calculate_mean_age(ages_list):
    mean_age=0
    for item in ages_list:
        mean_age= mean_age + item
    mean_age = mean_age / 30
    return mean_age

#---------------------
#Main - Start
ages_list = []
ages_list=create_ages_list()

print (ages_list)

ages_dist_l = []
ages_dist_l = create_age_dist_list(ages_list)

print(ages_dist_l)

max_age = calculate_max_age(ages_list)

print("The max age of the list is: " + str(max_age))

min_age = calculate_min_age(ages_list)

print("The min age of the list is: " + str(min_age))

mean_age = int(calculate_mean_age(ages_list))

print("The mean age of the list is: " + str(mean_age))

graphic_ages(["1 to 18", "19 to 40", "41 to 60", "60 and up"],ages_dist_l)