New Measure/Indicator for a Pattern

Hi All,

I am trying to achieve a measure/indicator. The problem is as below.

Let say a customer Spending pattern in the last 12 visits are $100/$20/$50/$40/$250/$60/$260/$150$/$20/$45/$22/$35.

I need a measure/indicator which tells me where the customer spending pattern is heading (increasing/Decreasing) visit on Visit.

Thanks for the help.