MS Excel - identify and conditional format pricing anomalies

This is a really simple and fast job for anyone who knows Excel well. I have an Excel spreadsheet that contains information on about 10,000 real estate properties. Each property has 20 years of tax assessment prices, broken down separately for the land and for the building so there are two values for each year. So there is a total of 40 columns, year by year in the pattern: land building land building land building land building

I need to identify the outliers - any properties that had abnormal changes in either the land or building value. It's that simple, just using one of the Excel commands to find the outliers.