Development of the number of indexed sources and documents in BASE since September 2004. Chart and Table will be updated every 2 months on the final day of the month.

| Month | Documents | Sources |
|---|---|---|
| September 2004 | 679,311 | 15 |
| November 2004 | 783,102 | 35 |
| January 2005 | 769,642 | 41 |
| March 2005 | 817,581 | 49 |
| May 2005 | 1,501,826 | 56 |
| July 2005 | 2,156,283 | 102 |
| September 2005 | 2,363,351 | 130 |
| November 2005 | 2,417,983 | 160 |
| January 2006 | 2,396,891 | 189 |
| March 2006 | 2,778,099 | 201 |
| May 2006 | 2,979,849 | 224 |
| July 2006 | 3,359,711 | 240 |
| September 2006 | 3,855,144 | 270 |
| November 2006 | 4,042,619 | 283 |
| January 2007 | 4,510,934 | 320 |
| March 2007 | 5,397,884 | 405 |
| May 2007 | 5,531,805 | 417 |
| July 2007 | 7,078,610 | 447 |
| September 2007 | 7,127,670 | 463 |
| November 2007 | 7,336,893 | 502 |
| January 2008 | 7,347,568 | 527 |
| March 2008 | 8,454,810 | 638 |
| May 2008 | 10,103,232 | 767 |
| July 2008 | 12,433,625 | 903 |
| September 2008 | 12,733,728 | 954 |
| November 2008 | 13,556,388 | 977 |
| January 2009 | 14,801,478 | 1027 |
| March 2009 | 18,372,311 | 1191 |
| May 2009 | 19,630,356 | 1242 |
| July 2009 | 20,517,820 | 1284 |
| September 2009 | 21,285,168 | 1346 |
| November 2009 | 21,514,939 | 1374 |
| January 2010 | 22,053,584 | 1405 |
| March 2010 | 23,244,312 | 1533 |
| May 2010 | 24,502,133 | 1666 |
| July 2010 | 25,232,582 | 1722 |
| September 2010 | 25,518,361 | 1730 |
| November 2010 | 25,508,112 | 1724 |
| January 2011 | 26,487,173 | 1693 |
| March 2011 | 26,920,383 | 1725 |
| May 2011 | 28,537,062 | 1837 |
| July 2011 | 31,177,636 | 1966 |
| September 2011 | 31,044,880 | 2026 |
| November 2011 | 33,414,799 | 2078 |
| January 2012 | 33,016,946 | 2107 |
| March 2012 | 34,291,810 | 2156 |
| May 2012 | 35,794,163 | 2201 |
| July 2012 | 37,199,958 | 2276 |
| November 2012 | 39,867,143 | 2390 |
| February 2013 | 42,585,595 | 2390 |