I feel like when you make an argument about how a thing that happened on a specific date in 1993 is the dominant reason for why a value that was low in the past

I feel like when you make an argument about how a thing that happened on a specific date in 1993 is the dominant reason for why a value that was low in the past is now high, you are more or less obliged to include a graph of average college cost over time and include a big marker for when your proposed change occurred. Not including that graph is suspicious because if it would have helped your case, you would have included it.