Prime gaps and last digit of prime numbers

Question

I recently saw a video about the last digit of prime numbers, that if a prime ends with a digit X then it is the least likely that the next prime also has X as the last digit.

But I counted the prime gaps (modulo 10) for primes between 200 million and 2 billion and the result is this:

• 0: 15885351
• 2: 19886835
• 4: 17246764
• 6: 18937346
• 8: 15265989

Why 0 is not the least common prime gap modulo 10? I expected it to be significantly less then any other gaps.

Edit1: Link to the numberphile video

Edit2: below the counts how many times the digit on the left is followed by the digit on the top (for the last digit of primes between 200 million and 2 billion):

        1       3       5       7       9
1 4047130 6467273       0 6526597 4763818
3 5250387 3896688       0 6133642 6525043
5       0       0       0       0       0
7 5557028 5885706       0 3893204 6469289
9 6950273 5556094       0 5251784 4048329

You see the counts in the main diagonal are much lower than any other.

Answer 1

There are only three last digits that can lead to a gap of $8$ while there are four that can lead to a gap of $10$. If the last digit of a prime is $7$, a gap of $8$ would lead to a number whose last digit is $5$, which cannot be prime. This suppresses gaps of $8$.