Helicopter Prison escape - fundamental query related to nested for loop

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My Code:

for x in data:
    for z in attempts_per_year:
        if z[0]== x[0]:
        
            z[1]+=1 
    
print(attempts_per_year)    

What I expected to happen:
I got the exact solution I was looking for . However my query is that this nested for loop worked since the years mentioned in the wiki data was arranged in ascending order - example 1971,1973,1978,1981,1981 etc .
What if the data wasn’t sorted in ascending order example - 1973,1971,1981,1971,1971,1981. This loop would not have had the same output i presume in such a case . Please tell me what could be the solution

What actually happened:

There was no error , the solution was exactly as i had expected

The output could be the same but in an unsorted manner.
When looping, we are iterating one element after the other.
data is al list of list, ie, the elements are lists in this list. The first element in this element (list) is the year.
attempts_per_year is a is also a list of list, where the first element of the lists is the year.

When looping data, we have a list as the element, for this list we check the first element (year) if it is similar to the first element also year when looping attempts per year

Hey Victor . Let’s take an example. Suppose the years in data is - 1973,1971,1973,1971,1971 ( arranged the same way ) . Let the years in attempts_per_year be arranged in ascending order , i.e 1971,1973,1978 . Now I write the below code and execute it

for x in data:
for z in attempts_per_year:
if z[0]== x[0]:

        z[1]+=1 

print(attempts_per_year)

The 1st iteration would check take 1973 as x[0] and compare with 1971 as z[0] . The output would be 1971 , 0

Question 1) Would the 2nd iteration check take x[0] as 1971 and compare with z[0] as 1971, and print the output as - 1971 , 0 ?
Question 2) Would would be the 3rd and 4th iteration and output ?