Do Detached Or Attached Homes Appreciate More Over Time?

Over the past five years, detached homes have increased slightly more in price (on average, per year) than attached homes (townhouses, duplexes, condos).
Detached homes have increased at an average of 6.1% per year from $200K to $269K while attached homes have increased at an average of 5.2% per year from $150K to $193K.
This (detached homes increasing in value more quickly over time) wouldn't necessarily always be the case if we looked back over the past 20 years -- we could likely find time periods when this were not true -- but we have seen some larger than normal swings in home values during some of those past 20 years.