Sullivan County Airport (IATA: SIV, ICAO: KSIV, FAA LID: SIV) is a county-owned public-use airport located three nautical miles (6 km) northwest of the central business district of Sullivan, a city in Sullivan County, Indiana, United States. It is included in the FAA's National Plan of Integrated Airport Systems for 2011–2015, which categorized it as a "general aviation" facility.

Based on that paragraph can we conclude that this sentence is true?
The Sullivan County Airport was included in the FAA's National Plan of Integrated Airport Systems for 4 years.
Yes