Some Facts from Property Tax Interim Report about Performance of UAM since 2004

PROPERTY TAX COLLECTION FROM 2002-03 TO 2009-10.
Financial Year    Amt.  (Rs.  In  Cr.) of   property tax      No. of properties.
2002-03                                726.49                                      922520
2003-04                                776.73                                      963119
2004-05                                575.76                                      945657
2005-06                                486.44                                      824884
2006-07                                495.69                                      842780
2007-08                                513.53                                      810832
2008-09                                606.10                                      862970
2009-10                                697.75                                      980589
(Source: A & C Deptt., MCD)

MY QUESTION FROM ALL OF YOU :

The House Tax was raised many times after the introduction of the Unit Area Method. Than how it's possible that  not only the collections reduced but the number of properties paying house tax also reduced ?