Table 1.
The descriptive statistics of the diffusion progression from 1998 to 2015, including cases, sub-clusters(SC), progression links(PL), and chains. The SC size represents the median number of cases within a sub-cluster; chain size represents the median number of sub-clusters within a chain; the SC duration represents the median temporal duration of the sub-clusters, which measures the number of days between the earliest and the latest cases within a sub-cluster; the chain duration represents the median temporal duration of the chains. The numbers in brackets are the median absolute deviation (MAD) of the corresponding columns.
| year | no. cases | no. SC | SC size | SC duration | no. iso-SC | no. PL | no. chains | chain size | chain duration |
|---|---|---|---|---|---|---|---|---|---|
| 1998 | 113 | 5 | 3 (0) | 5 (4) | 2 | 2 | 1 | 3.0 (0) | 66.0 (0) |
| 1999 | 20 | 1 | — | — | 1 | 0 | 0 | — | — |
| 2000 | — | — | — | — | — | — | — | — | — |
| 2001 | 220 | 9 | 8 (9) | 14 (15) | 3 | 8 | 1 | 6 (0) | 81 (0) |
| 2002 | 4671 | 276 | 3 (1) | 7 (6) | 52 | 198 | 39 | 2 (0) | 36 (22) |
| 2003 | 34 | 2 | 2 (0) | 2 (2) | 2 | 0 | 0 | — | — |
| 2004 | 56 | 1 | — | — | 1 | 0 | 0 | — | — |
| 2005 | 96 | 6 | 4 (1) | 6 (4) | 4 | 1 | 1 | 2 (0) | 19 (0) |
| 2006 | 955 | 102 | 3 (1) | 4 (4) | 21 | 57 | 25 | 3 (1) | 29 (18) |
| 2007 | 168 | 7 | 4 (1) | 12 (9) | 3 | 2 | 2 | 2 (0) | 31 (1) |
| 2008 | 417 | 31 | 3 (1) | 5 (6) | 18 | 7 | 6 | 2 (0) | 23 (7) |
| 2009 | 751 | 75 | 3 (1) | 6 (6) | 11 | 52 | 17 | 3 (1) | 36 (16) |
| 2010 | 1044 | 129 | 3 (1) | 5 (4) | 36 | 68 | 28 | 3 (1) | 35 (16) |
| 2011 | 1158 | 119 | 3 (1) | 5 (6) | 34 | 61 | 25 | 2 (0) | 34 (16) |
| 2012 | 478 | 37 | 3 (1) | 5 (4) | 18 | 15 | 6 | 2 (0) | 26 (9) |
| 2013 | 64 | 3 | 3 (0) | 3 (1) | 1 | 1 | 1 | 2 (0) | 17.0 (0) |
| 2014 | 15011 | 433 | 3 (1) | 5 (4) | 99 | 292 | 56 | 2 (0) | 39 (19) |
| 2015 | 19520 | 484 | 3 (1) | 5 (4) | 115 | 356 | 44 | 3 (1) | 50 (36) |