Quarter	Number of Buildings
1975-01-01	16139
1975-04-01	21578
1975-07-01	14538
1975-10-01	22244
1976-01-01	12909
1976-04-01	16642
1976-07-01	10770
1976-10-01	15491
1977-01-01	14313
1977-04-01	16812
1977-07-01	9811
1977-10-01	13942
1978-01-01	12579
1978-04-01	15758
1978-07-01	10133
1978-10-01	15272
1979-01-01	13087
1979-04-01	15488
1979-07-01	11330
1979-10-01	15586
1980-01-01	12449
1980-04-01	13429
1980-07-01	10972
1980-10-01	14588
1981-01-01	12967
1981-04-01	13675
1981-07-01	11848
1981-10-01	13107
1982-01-01	11686
1982-04-01	11946
1982-07-01	8589
1982-10-01	12887
1983-01-01	12300
1983-04-01	11294
1983-07-01	8177
1983-10-01	11593
1984-01-01	10270
1984-04-01	8432
1984-07-01	6898
1984-10-01	9388
1985-01-01	9477
1985-04-01	8156
1985-07-01	6806
1985-10-01	8493
1986-01-01	7963
1986-04-01	8136
1986-07-01	5628
1986-10-01	7064
1987-01-01	8059
1987-04-01	7215
1987-07-01	7066
1987-10-01	8545
1988-01-01	9151
1988-04-01	10948
1988-07-01	9023
1988-10-01	11453
1989-01-01	12473
1989-04-01	14131
1989-07-01	9395
1989-10-01	14405
1990-01-01	14688
1990-04-01	16540
1990-07-01	13193
1990-10-01	14026
1991-01-01	18113
1991-04-01	17974
1991-07-01	13922
1991-10-01	16877
1992-01-01	17469
1992-04-01	14712
1992-07-01	11127
1992-10-01	14011
1993-01-01	11838
1993-04-01	9501
1993-07-01	5978
1993-10-01	7771
1994-01-01	8171
1994-04-01	4978
1994-07-01	3371
1994-10-01	5110
1995-01-01	4345
1995-04-01	2584
1995-07-01	2856
1995-10-01	2893
1996-01-01	4126
1996-04-01	2529
1996-07-01	2769
1996-10-01	3661
1997-01-01	4258
1997-04-01	4254
1997-07-01	1871
1997-10-01	2624
1998-01-01	3102
1998-04-01	2605
1998-07-01	2523
1998-10-01	3229
1999-01-01	3211
1999-04-01	3126
1999-07-01	1952
1999-10-01	3423
2000-01-01	3808
2000-04-01	2647
2000-07-01	2401
2000-10-01	4128
2001-01-01	4566
2001-04-01	3161
2001-07-01	3298
2001-10-01	4386
2002-01-01	5829
2002-04-01	3930
2002-07-01	3890
2002-10-01	6292
2003-01-01	5394
2003-04-01	4416
2003-07-01	4307
2003-10-01	5869
2004-01-01	7148
2004-04-01	5505
2004-07-01	5041
2004-10-01	7589
2005-01-01	5383
2005-04-01	5829
2005-07-01	4769
2005-10-01	7087
2006-01-01	6876
2006-04-01	6447
2006-07-01	6850
2006-10-01	9659
2007-01-01	6264
2007-04-01	7038
2007-07-01	6757
2007-10-01	10468
2008-01-01	7665
2008-04-01	7211
2008-07-01	6811
2008-10-01	10334
2009-01-01	7824
2009-04-01	5308
2009-07-01	4080
2009-10-01	5609
2010-01-01	6269
2010-04-01	4315
2010-07-01	3907
2010-10-01	5009
2011-01-01	5253
2011-04-01	4751
2011-07-01	4092
2011-10-01	5968
2012-01-01	9506
2012-04-01	4858
2012-07-01	4515
2012-10-01	7114
2013-01-01	9503
2013-04-01	6259
2013-07-01	5137
2013-10-01	6380