On the 1973 the punch was used with a hammer.

If the mint mark was not struck deep enough it would look like your coin. If it was struck deeply into the die, then it would be stronger. This was done by hand until 1989. In 1990 forward the mint marks are part of the design. (all the mint marks for the same year would be the same strength and same location from 1990 forward. In 2008 the mint mark changed it shape.

So comparing to a different year is sometimes as different as apples and oranges. Compare with coins of the same year.