1997: 183 buildings, average cost: $62,900

1998: 224 buildings, average cost: $51,600

1999: 163 buildings, average cost: $60,300

2000: 127 buildings, average cost: $69,400

2001: 141 buildings, average cost: $84,500

2002: 254 buildings, average cost: $98,500

2003: 320 buildings, average cost: $103,000

2004: 196 buildings, average cost: $129,800

2005: 256 buildings, average cost: $122,900

2006: 427 buildings, average cost: $108,600

2007: 365 buildings, average cost: $93,900

2008: 216 buildings, average cost: $102,400

2009: 118 buildings, average cost: $94,800

2010: 73 buildings, average cost: $91,800

2011: 67 buildings, average cost: $86,300